[PATCH v5 00/28] KVM: combined patchset for MBEC/GMET support

[PATCH v5 00/28] KVM: combined patchset for MBEC/GMET support

[Paolo Bonzini]

I will once more send you to v3 (https://lore.kernel.org/kvm/20260408154217.458420-1-pbonzini@redhat.com/)
for the description of the series.

v4 incorrectly rebased onto 7.1 KVM and broke the case where L1 disables
NPT.  On top of that I made a few final touches on the patch split, and
opted to use the XU bit unconditionally in the MMU even if MBEC is disabled.
This is more consistent with the idea of reducing as much as possible
the differences between mbec=0 and mbec=1 modes.

Paolo

v4->v5:
- patches 8 and 9: swap to clarify use of ACC_USER_MASK to detect read faults
- patch 11: fix final argument to kvm_translate_gpa (using pte_access instead
  of walker->pte_access worked more or less accidentally, but it is incorrect
  because vmx_translate_nested_gpa uses ACC_* constants rather than PT_*)
- patches 13 and 15: revert to always setting shadow_xu_mask ==
  VMX_EPT_USER_EXECUTABLE_MASK, even if MBEC is disabled.  The MMU always
  operates as if MBEC is available, instead of complicating its life (and
  potentially introducing bugs) by mapping XU onto X; blocking incorrect
  configuration can be done at higher levels.  Add a comment on the design.
- patch 24: also block CR4.SMAP
- patches 26 and 28: fix rebase onto 7.1 KVM (fixes nested NPT disabled)

v3->v4:
- patch 15: clear enable_mbec = 0 if enable_ept == 0
- patches 23-27: adjust for rename of nested_ctl to misc_ctl
- patch 24: new
- patch 27: disable svm_get_cpl for SEV-ES/SEV-SNP
- patch 28: fix commit message reference to __nested_svm_check_controls 


Jon Kohler (5):
  KVM: TDX/VMX: rework EPT_VIOLATION_EXEC_FOR_RING3_LIN into PROT_MASK
  KVM: x86/mmu: remove SPTE_PERM_MASK
  KVM: x86/mmu: free up bit 10 of PTEs in preparation for MBEC
  KVM: nVMX: advertise MBEC to nested guests
  KVM: nVMX: allow MBEC with EVMCS

Paolo Bonzini (23):
  KVM: x86/mmu: shuffle high bits of SPTEs in preparation for MBEC
  KVM: x86/mmu: remove SPTE_EPT_*
  KVM: x86/mmu: merge make_spte_{non,}executable
  KVM: x86/mmu: rename and clarify BYTE_MASK
  KVM: x86/mmu: separate more EPT/non-EPT permission_fault()
  KVM: x86/mmu: introduce ACC_READ_MASK
  KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa
  KVM: x86/mmu: pass pte_access for final nGPA->GPA walk
  KVM: x86: make translate_nested_gpa vendor-specific
  KVM: x86/mmu: split XS/XU bits for EPT
  KVM: x86/mmu: move cr4_smep to base role
  KVM: VMX: enable use of MBEC
  KVM: nVMX: pass advanced EPT violation vmexit info to guest
  KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations
  KVM: x86/mmu: add support for MBEC to EPT page table walks
  KVM: x86/mmu: propagate access mask from root pages down
  KVM: x86/mmu: introduce cpu_role bit for availability of PFEC.I/D
  KVM: SVM: add GMET bit definitions
  KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu
  KVM: x86/mmu: add support for GMET to NPT page table walks
  KVM: SVM: enable GMET and set it in MMU role
  KVM: SVM: work around errata 1218
  KVM: nSVM: enable GMET for guests

 Documentation/virt/kvm/x86/mmu.rst |  10 +-
 arch/x86/include/asm/cpufeatures.h |   1 +
 arch/x86/include/asm/kvm-x86-ops.h |   1 +
 arch/x86/include/asm/kvm_host.h    |  48 +++++---
 arch/x86/include/asm/svm.h         |   1 +
 arch/x86/include/asm/vmx.h         |  14 ++-
 arch/x86/kvm/hyperv.c              |   4 +-
 arch/x86/kvm/mmu.h                 |  30 +++--
 arch/x86/kvm/mmu/mmu.c             | 176 ++++++++++++++++++++---------
 arch/x86/kvm/mmu/mmutrace.h        |  19 ++--
 arch/x86/kvm/mmu/paging_tmpl.h     |  73 ++++++++----
 arch/x86/kvm/mmu/spte.c            |  92 +++++++++------
 arch/x86/kvm/mmu/spte.h            |  70 +++++++-----
 arch/x86/kvm/mmu/tdp_mmu.c         |   6 +-
 arch/x86/kvm/svm/nested.c          |  38 ++++++-
 arch/x86/kvm/svm/svm.c             |  31 +++++
 arch/x86/kvm/svm/svm.h             |   1 +
 arch/x86/kvm/vmx/capabilities.h    |  12 +-
 arch/x86/kvm/vmx/common.h          |  20 ++--
 arch/x86/kvm/vmx/hyperv_evmcs.h    |   1 +
 arch/x86/kvm/vmx/main.c            |   9 ++
 arch/x86/kvm/vmx/nested.c          |  46 +++++++-
 arch/x86/kvm/vmx/tdx.c             |   2 +-
 arch/x86/kvm/vmx/vmx.c             |  27 ++++-
 arch/x86/kvm/vmx/vmx.h             |   1 +
 arch/x86/kvm/vmx/x86_ops.h         |   1 +
 arch/x86/kvm/x86.c                 |  18 +--
 27 files changed, 529 insertions(+), 223 deletions(-)

-- 
2.52.0

[PATCH 01/28] KVM: TDX/VMX: rework EPT_VIOLATION_EXEC_FOR_RING3_LIN into PROT_MASK

[Paolo Bonzini]

From: Jon Kohler <jon@nutanix.com>

EPT exit qualification bit 6 is used when mode-based execute control
is enabled, and reflects user executable addresses. Rework name to
reflect the intention and add to EPT_VIOLATION_PROT_MASK, which allows
simplifying the return evaluation in
tdx_is_sept_violation_unexpected_pending a pinch.

Rework handling in __vmx_handle_ept_violation to unconditionally clear
EPT_VIOLATION_PROT_USER_EXEC until MBEC is implemented, as suggested by
Sean [1].

Note: Intel SDM Table 29-7 defines bit 6 as:
  If the "mode-based execute control" VM-execution control is 0, the
  value of this bit is undefined. If that control is 1, this bit is the
  logical-AND of bit 10 in the EPT paging-structure entries used to
  translate the guest-physical address of the access causing the EPT
  violation. In this case, it indicates whether the guest-physical
  address was executable for user-mode linear addresses.

[1] https://lore.kernel.org/all/aCJDzU1p_SFNRIJd@google.com/

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jon Kohler <jon@nutanix.com>
Message-ID: <20251223054806.1611168-2-jon@nutanix.com>
Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/vmx.h | 5 +++--
 arch/x86/kvm/vmx/common.h  | 9 +++++++--
 arch/x86/kvm/vmx/tdx.c     | 2 +-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 37080382df54..b2291a766e3f 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -608,10 +608,11 @@ enum vm_entry_failure_code {
 #define EPT_VIOLATION_PROT_READ		BIT(3)
 #define EPT_VIOLATION_PROT_WRITE	BIT(4)
 #define EPT_VIOLATION_PROT_EXEC		BIT(5)
-#define EPT_VIOLATION_EXEC_FOR_RING3_LIN BIT(6)
+#define EPT_VIOLATION_PROT_USER_EXEC	BIT(6)
 #define EPT_VIOLATION_PROT_MASK		(EPT_VIOLATION_PROT_READ  | \
 					 EPT_VIOLATION_PROT_WRITE | \
-					 EPT_VIOLATION_PROT_EXEC)
+					 EPT_VIOLATION_PROT_EXEC  | \
+					 EPT_VIOLATION_PROT_USER_EXEC)
 #define EPT_VIOLATION_GVA_IS_VALID	BIT(7)
 #define EPT_VIOLATION_GVA_TRANSLATED	BIT(8)
 
diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index 412d0829d7a2..adf925500b9e 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -94,8 +94,13 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
 	/* Is it a fetch fault? */
 	error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
 		      ? PFERR_FETCH_MASK : 0;
-	/* ept page table entry is present? */
-	error_code |= (exit_qualification & EPT_VIOLATION_PROT_MASK)
+	/*
+	 * ept page table entry is present?
+	 * note: unconditionally clear USER_EXEC until mode-based
+	 * execute control is implemented
+	 */
+	error_code |= (exit_qualification &
+		       (EPT_VIOLATION_PROT_MASK & ~EPT_VIOLATION_PROT_USER_EXEC))
 		      ? PFERR_PRESENT_MASK : 0;
 
 	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 1e47c194af53..89f9fe30435d 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1845,7 +1845,7 @@ static inline bool tdx_is_sept_violation_unexpected_pending(struct kvm_vcpu *vcp
 	if (eeq_type != TDX_EXT_EXIT_QUAL_TYPE_PENDING_EPT_VIOLATION)
 		return false;
 
-	return !(eq & EPT_VIOLATION_PROT_MASK) && !(eq & EPT_VIOLATION_EXEC_FOR_RING3_LIN);
+	return !(eq & EPT_VIOLATION_PROT_MASK);
 }
 
 static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu)
-- 
2.52.0

[PATCH 02/28] KVM: x86/mmu: remove SPTE_PERM_MASK

[Paolo Bonzini]

From: Jon Kohler <jon@nutanix.com>

SPTE_PERM_MASK is no longer referenced by anything in the kernel.

Signed-off-by: Jon Kohler <jon@nutanix.com>
Message-ID: <20251223054806.1611168-3-jon@nutanix.com>
Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/spte.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 91ce29fd6f1b..28086fa86fe0 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -42,9 +42,6 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
 #define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
 #endif
 
-#define SPTE_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \
-			| shadow_x_mask | shadow_nx_mask | shadow_me_mask)
-
 #define ACC_EXEC_MASK    1
 #define ACC_WRITE_MASK   PT_WRITABLE_MASK
 #define ACC_USER_MASK    PT_USER_MASK
-- 
2.52.0

[PATCH 03/28] KVM: x86/mmu: free up bit 10 of PTEs in preparation for MBEC

[Paolo Bonzini]

From: Jon Kohler <jon@nutanix.com>

Update SPTE_MMIO_ALLOWED_MASK to allow EPT user executable (bit 10) to
be treated like EPT RWX bit2:0, as when mode-based execute control is
enabled, bit 10 can act like a "present" bit.  Likewise do not include
it in FROZEN_SPTE.

No functional changes intended, other than the reduction of the maximum
MMIO generation that is stored in page tables.

Cc: Kai Huang <kai.huang@intel.com>
Signed-off-by: Jon Kohler <jon@nutanix.com>
Message-ID: <20251223054806.1611168-4-jon@nutanix.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/vmx.h |  2 ++
 arch/x86/kvm/mmu/spte.h    | 20 +++++++++++---------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index b2291a766e3f..2b30b921b375 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -560,10 +560,12 @@ enum vmcs_field {
 #define VMX_EPT_ACCESS_BIT			(1ull << 8)
 #define VMX_EPT_DIRTY_BIT			(1ull << 9)
 #define VMX_EPT_SUPPRESS_VE_BIT			(1ull << 63)
+
 #define VMX_EPT_RWX_MASK                        (VMX_EPT_READABLE_MASK |       \
 						 VMX_EPT_WRITABLE_MASK |       \
 						 VMX_EPT_EXECUTABLE_MASK)
 #define VMX_EPT_MT_MASK				(7ull << VMX_EPT_MT_EPTE_SHIFT)
+#define VMX_EPT_USER_EXECUTABLE_MASK		(1ull << 10)
 
 static inline u8 vmx_eptp_page_walk_level(u64 eptp)
 {
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 28086fa86fe0..4283cea3e66c 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -96,11 +96,11 @@ static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK));
 #undef SHADOW_ACC_TRACK_SAVED_MASK
 
 /*
- * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of
+ * Due to limited space in PTEs, the MMIO generation is an 18 bit subset of
  * the memslots generation and is derived as follows:
  *
- * Bits 0-7 of the MMIO generation are propagated to spte bits 3-10
- * Bits 8-18 of the MMIO generation are propagated to spte bits 52-62
+ * Bits 0-6 of the MMIO generation are propagated to spte bits 3-9
+ * Bits 7-17 of the MMIO generation are propagated to spte bits 52-62
  *
  * The KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS flag is intentionally not included in
  * the MMIO generation number, as doing so would require stealing a bit from
@@ -111,7 +111,7 @@ static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK));
  */
 
 #define MMIO_SPTE_GEN_LOW_START		3
-#define MMIO_SPTE_GEN_LOW_END		10
+#define MMIO_SPTE_GEN_LOW_END		9
 
 #define MMIO_SPTE_GEN_HIGH_START	52
 #define MMIO_SPTE_GEN_HIGH_END		62
@@ -133,7 +133,8 @@ static_assert(!(SPTE_MMU_PRESENT_MASK &
  * and so they're off-limits for generation; additional checks ensure the mask
  * doesn't overlap legal PA bits), and bit 63 (carved out for future usage).
  */
-#define SPTE_MMIO_ALLOWED_MASK (BIT_ULL(63) | GENMASK_ULL(51, 12) | GENMASK_ULL(2, 0))
+#define SPTE_MMIO_ALLOWED_MASK (BIT_ULL(63) | GENMASK_ULL(51, 12) | \
+				BIT_ULL(10) | GENMASK_ULL(2, 0))
 static_assert(!(SPTE_MMIO_ALLOWED_MASK &
 		(SPTE_MMU_PRESENT_MASK | MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK)));
 
@@ -141,7 +142,7 @@ static_assert(!(SPTE_MMIO_ALLOWED_MASK &
 #define MMIO_SPTE_GEN_HIGH_BITS		(MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1)
 
 /* remember to adjust the comment above as well if you change these */
-static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11);
+static_assert(MMIO_SPTE_GEN_LOW_BITS == 7 && MMIO_SPTE_GEN_HIGH_BITS == 11);
 
 #define MMIO_SPTE_GEN_LOW_SHIFT		(MMIO_SPTE_GEN_LOW_START - 0)
 #define MMIO_SPTE_GEN_HIGH_SHIFT	(MMIO_SPTE_GEN_HIGH_START - MMIO_SPTE_GEN_LOW_BITS)
@@ -217,10 +218,11 @@ extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask;
  *
  * Only used by the TDP MMU.
  */
-#define FROZEN_SPTE	(SHADOW_NONPRESENT_VALUE | 0x5a0ULL)
+#define FROZEN_SPTE	(SHADOW_NONPRESENT_VALUE | 0x1a0ULL)
 
-/* Frozen SPTEs must not be misconstrued as shadow present PTEs. */
-static_assert(!(FROZEN_SPTE & SPTE_MMU_PRESENT_MASK));
+/* Frozen SPTEs must not be misconstrued as shadow or MMU present PTEs. */
+static_assert(!(FROZEN_SPTE & (SPTE_MMU_PRESENT_MASK |
+			       VMX_EPT_RWX_MASK | VMX_EPT_USER_EXECUTABLE_MASK)));
 
 static inline bool is_frozen_spte(u64 spte)
 {
-- 
2.52.0

Re: [PATCH 03/28] KVM: x86/mmu: free up bit 10 of PTEs in preparation for MBEC

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> From: Jon Kohler <jon@nutanix.com>
> 
> Update SPTE_MMIO_ALLOWED_MASK to allow EPT user executable (bit 10) to
> be treated like EPT RWX bit2:0, as when mode-based execute control is
> enabled, bit 10 can act like a "present" bit.
 
For posterity, this matters because MMIO SPTEs for TDX need to be RWX=0 in order
to generate #VEs on any access (hardware never reflects EPT Misconfigs as #VEs).
Arguably we could delay this until the TDX-Module enables MBEC (or maybe that's
already in the works?), because even though KVM enables MBEC, that only matters
for non-TDX guests.

But I don't see any point in delaying the inevitable.

[PATCH 04/28] KVM: x86/mmu: shuffle high bits of SPTEs in preparation for MBEC

[Paolo Bonzini]

Access tracking will need to save bit 10 when MBEC is enabled.
Right now it is simply shifting the R and X bits into bits 54 and 56,
but bit 10 would not fit with the same scheme.  Reorganize the
high bits so that access tracking will use bits 52, 54 and 62.
As a side effect, the free bits are compacted slightly, with
56-59 still unused.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/spte.h | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 4283cea3e66c..317b9cd1537c 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -17,10 +17,20 @@
  */
 #define SPTE_MMU_PRESENT_MASK		BIT_ULL(11)
 
+/*
+ * The ignored high bits are allocated as follows:
+ * - bits 52, 54: saved X-R bits for access tracking when EPT does not have A/D
+ * - bits 53 (EPT only): host writable
+ * - bits 55 (EPT only): MMU-writable
+ * - bits 56-59: unused
+ * - bits 60-61: type of A/D tracking
+ * - bits 62: unused
+ */
+
 /*
  * TDP SPTES (more specifically, EPT SPTEs) may not have A/D bits, and may also
  * be restricted to using write-protection (for L2 when CPU dirty logging, i.e.
- * PML, is enabled).  Use bits 52 and 53 to hold the type of A/D tracking that
+ * PML, is enabled).  Use bits 60 and 61 to hold the type of A/D tracking that
  * is must be employed for a given TDP SPTE.
  *
  * Note, the "enabled" mask must be '0', as bits 62:52 are _reserved_ for PAE
@@ -29,7 +39,7 @@
  * TDP with CPU dirty logging (PML).  If NPT ever gains PML-like support, it
  * must be restricted to 64-bit KVM.
  */
-#define SPTE_TDP_AD_SHIFT		52
+#define SPTE_TDP_AD_SHIFT		60
 #define SPTE_TDP_AD_MASK		(3ULL << SPTE_TDP_AD_SHIFT)
 #define SPTE_TDP_AD_ENABLED		(0ULL << SPTE_TDP_AD_SHIFT)
 #define SPTE_TDP_AD_DISABLED		(1ULL << SPTE_TDP_AD_SHIFT)
@@ -65,7 +75,7 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
  */
 #define SHADOW_ACC_TRACK_SAVED_BITS_MASK (SPTE_EPT_READABLE_MASK | \
 					  SPTE_EPT_EXECUTABLE_MASK)
-#define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 54
+#define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 52
 #define SHADOW_ACC_TRACK_SAVED_MASK	(SHADOW_ACC_TRACK_SAVED_BITS_MASK << \
 					 SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
 static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK));
@@ -84,8 +94,8 @@ static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK));
  * to not overlap the A/D type mask or the saved access bits of access-tracked
  * SPTEs when A/D bits are disabled.
  */
-#define EPT_SPTE_HOST_WRITABLE		BIT_ULL(57)
-#define EPT_SPTE_MMU_WRITABLE		BIT_ULL(58)
+#define EPT_SPTE_HOST_WRITABLE		BIT_ULL(53)
+#define EPT_SPTE_MMU_WRITABLE		BIT_ULL(55)
 
 static_assert(!(EPT_SPTE_HOST_WRITABLE & SPTE_TDP_AD_MASK));
 static_assert(!(EPT_SPTE_MMU_WRITABLE & SPTE_TDP_AD_MASK));
-- 
2.52.0

Re: [PATCH 04/28] KVM: x86/mmu: shuffle high bits of SPTEs in preparation for MBEC

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> Access tracking will need to save bit 10 when MBEC is enabled.
> Right now it is simply shifting the R and X bits into bits 54 and 56,
> but bit 10 would not fit with the same scheme.  Reorganize the
> high bits so that access tracking will use bits 52, 54 and 62.
> As a side effect, the free bits are compacted slightly, with
> 56-59 still unused.

> @@ -84,8 +94,8 @@ static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK));
>   * to not overlap the A/D type mask or the saved access bits of access-tracked
>   * SPTEs when A/D bits are disabled.
>   */
> -#define EPT_SPTE_HOST_WRITABLE		BIT_ULL(57)
> -#define EPT_SPTE_MMU_WRITABLE		BIT_ULL(58)

FWIW, I originally chose bits 57 and 58 so that HOST-writable and MMU-writable
would occupy the high byte, e.g. for faster access (in theory).  But that's
uninteresting in practice because the mask is stored in a global variable, i.e.
the compiler can't optimize the SPTE access anyways.

[PATCH 05/28] KVM: x86/mmu: remove SPTE_EPT_*

[Paolo Bonzini]

spte.h is already including vmx.h, use the constants it defines.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/spte.h | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 317b9cd1537c..bc02a2e89a31 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -57,10 +57,6 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
 #define ACC_USER_MASK    PT_USER_MASK
 #define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
 
-/* The mask for the R/X bits in EPT PTEs */
-#define SPTE_EPT_READABLE_MASK			0x1ull
-#define SPTE_EPT_EXECUTABLE_MASK		0x4ull
-
 #define SPTE_LEVEL_BITS			9
 #define SPTE_LEVEL_SHIFT(level)		__PT_LEVEL_SHIFT(level, SPTE_LEVEL_BITS)
 #define SPTE_INDEX(address, level)	__PT_INDEX(address, level, SPTE_LEVEL_BITS)
@@ -73,8 +69,8 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
  * restored only when a write is attempted to the page.  This mask obviously
  * must not overlap the A/D type mask.
  */
-#define SHADOW_ACC_TRACK_SAVED_BITS_MASK (SPTE_EPT_READABLE_MASK | \
-					  SPTE_EPT_EXECUTABLE_MASK)
+#define SHADOW_ACC_TRACK_SAVED_BITS_MASK (VMX_EPT_READABLE_MASK | \
+					  VMX_EPT_EXECUTABLE_MASK)
 #define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 52
 #define SHADOW_ACC_TRACK_SAVED_MASK	(SHADOW_ACC_TRACK_SAVED_BITS_MASK << \
 					 SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
-- 
2.52.0

[PATCH 06/28] KVM: x86/mmu: merge make_spte_{non,}executable

[Paolo Bonzini]

As the logic will become more complicated with the introduction
of MBEC, at least write it only once.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/spte.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 85a0473809b0..e9dc0ae44274 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -317,14 +317,16 @@ static u64 modify_spte_protections(u64 spte, u64 set, u64 clear)
 	return spte;
 }
 
-static u64 make_spte_executable(u64 spte)
+static u64 make_spte_executable(u64 spte, u8 access)
 {
-	return modify_spte_protections(spte, shadow_x_mask, shadow_nx_mask);
-}
+	u64 set, clear;
 
-static u64 make_spte_nonexecutable(u64 spte)
-{
-	return modify_spte_protections(spte, shadow_nx_mask, shadow_x_mask);
+	if (access & ACC_EXEC_MASK)
+		set = shadow_x_mask;
+	else
+		set = shadow_nx_mask;
+	clear = set ^ (shadow_nx_mask | shadow_x_mask);
+	return modify_spte_protections(spte, set, clear);
 }
 
 /*
@@ -356,8 +358,8 @@ u64 make_small_spte(struct kvm *kvm, u64 huge_spte,
 		 * the page executable as the NX hugepage mitigation no longer
 		 * applies.
 		 */
-		if ((role.access & ACC_EXEC_MASK) && is_nx_huge_page_enabled(kvm))
-			child_spte = make_spte_executable(child_spte);
+		if (is_nx_huge_page_enabled(kvm))
+			child_spte = make_spte_executable(child_spte, role.access);
 	}
 
 	return child_spte;
@@ -379,7 +381,7 @@ u64 make_huge_spte(struct kvm *kvm, u64 small_spte, int level)
 	huge_spte &= KVM_HPAGE_MASK(level) | ~PAGE_MASK;
 
 	if (is_nx_huge_page_enabled(kvm))
-		huge_spte = make_spte_nonexecutable(huge_spte);
+		huge_spte = make_spte_executable(huge_spte, 0);
 
 	return huge_spte;
 }
-- 
2.52.0

Re: [PATCH 06/28] KVM: x86/mmu: merge make_spte_{non,}executable

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> As the logic will become more complicated with the introduction
> of MBEC, at least write it only once.
> 
> Tested-by: David Riley <d.riley@proxmox.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/mmu/spte.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
> index 85a0473809b0..e9dc0ae44274 100644
> --- a/arch/x86/kvm/mmu/spte.c
> +++ b/arch/x86/kvm/mmu/spte.c
> @@ -317,14 +317,16 @@ static u64 modify_spte_protections(u64 spte, u64 set, u64 clear)
>  	return spte;
>  }
>  
> -static u64 make_spte_executable(u64 spte)
> +static u64 make_spte_executable(u64 spte, u8 access)

make_spte_executable() is a less-than-awesome name for the combined functionality.
I read it as "Make an executable SPTE", but when called from make_huge_spte() it's
obviously not making an executable SPTE.

What about something like this, either as fixup or on top? (completely untested)

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 9b5ce4d1fa65..84d716e91566 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -320,10 +320,13 @@ static u64 modify_spte_protections(u64 spte, u64 set, u64 clear)
        return spte;
 }
 
-static u64 make_spte_executable(u64 spte, u8 access)
+static u64 apply_nx_huge_page_adjustments(struct kvm *kvm, u64 spte, u8 access)
 {
        u64 set, clear;
 
+       if (!is_nx_huge_page_enabled(kvm))
+               return spte;
+
        if (shadow_nx_mask)
                set = (access & ACC_EXEC_MASK) ? 0 : shadow_nx_mask;
        else
@@ -363,8 +366,8 @@ u64 make_small_spte(struct kvm *kvm, u64 huge_spte,
                 * the page executable as the NX hugepage mitigation no longer
                 * applies.
                 */
-               if (is_nx_huge_page_enabled(kvm))
-                       child_spte = make_spte_executable(child_spte, role.access);
+               child_spte = apply_nx_huge_page_adjustments(kvm, child_spte,
+                                                           role.access);
        }
 
        return child_spte;
@@ -384,11 +387,7 @@ u64 make_huge_spte(struct kvm *kvm, u64 small_spte, int level)
         * huge page address.
         */
        huge_spte &= KVM_HPAGE_MASK(level) | ~PAGE_MASK;
-
-       if (is_nx_huge_page_enabled(kvm))
-               huge_spte = make_spte_executable(huge_spte, 0);
-
-       return huge_spte;
+       return apply_nx_huge_page_adjustments(kvm, huge_spte, 0);
 }
 
 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled)

Re: [PATCH 06/28] KVM: x86/mmu: merge make_spte_{non,}executable

[Paolo Bonzini]

On Thu, Apr 30, 2026 at 8:22 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> > As the logic will become more complicated with the introduction
> > of MBEC, at least write it only once.
> >
> > Tested-by: David Riley <d.riley@proxmox.com>
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > ---
> >  arch/x86/kvm/mmu/spte.c | 20 +++++++++++---------
> >  1 file changed, 11 insertions(+), 9 deletions(-)
> >
> > diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
> > index 85a0473809b0..e9dc0ae44274 100644
> > --- a/arch/x86/kvm/mmu/spte.c
> > +++ b/arch/x86/kvm/mmu/spte.c
> > @@ -317,14 +317,16 @@ static u64 modify_spte_protections(u64 spte, u64 set, u64 clear)
> >       return spte;
> >  }
> >
> > -static u64 make_spte_executable(u64 spte)
> > +static u64 make_spte_executable(u64 spte, u8 access)
>
> make_spte_executable() is a less-than-awesome name for the combined functionality.
> I read it as "Make an executable SPTE", but when called from make_huge_spte() it's
> obviously not making an executable SPTE.
>
> What about something like this, either as fixup or on top? (completely untested)

I'll keep my code but rename to change_spte_executable().

Paolo

[PATCH 07/28] KVM: x86/mmu: rename and clarify BYTE_MASK

[Paolo Bonzini]

The BYTE_MASK macro is the central point of the black magic
in update_permission_bitmask().  Rename it to something
that relates to how it is used, and add a comment explaining
how it works.

Using shifts instead of powers of two was actually suggested by
David Hildenbrand back in 2017 for clarity[1] but I evidently
forgot his suggestion when applying to kvm.git.

[1] https://lore.kernel.org/kvm/e4b5df86-31ae-2f4e-0666-393753e256df@redhat.com/

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/mmu.c | 55 ++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 24fbc9ea502a..70fd6868a555 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5529,29 +5529,53 @@ reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly)
 				    max_huge_page_level);
 }
 
-#define BYTE_MASK(access) \
-	((1 & (access) ? 2 : 0) | \
-	 (2 & (access) ? 4 : 0) | \
-	 (3 & (access) ? 8 : 0) | \
-	 (4 & (access) ? 16 : 0) | \
-	 (5 & (access) ? 32 : 0) | \
-	 (6 & (access) ? 64 : 0) | \
-	 (7 & (access) ? 128 : 0))
-
+/*
+ * Build a mask with all combinations of PTE access rights that
+ * include the given access bit.  The mask can be queried with
+ * "mask & (1 << access)", where access is a combination of
+ * ACC_* bits.
+ *
+ * By mixing and matching multiple masks returned by ACC_BITS_MASK,
+ * update_permission_bitmask() builds what is effectively a
+ * two-dimensional array of bools.  The second dimension is
+ * provided by individual bits of permissions[pfec >> 1], and
+ * logical &, | and ~ operations operate on all the 8 possible
+ * combinations of ACC_* bits.
+ */
+#define ACC_BITS_MASK(access) \
+	((1 & (access) ? 1 << 1 : 0) | \
+	 (2 & (access) ? 1 << 2 : 0) | \
+	 (3 & (access) ? 1 << 3 : 0) | \
+	 (4 & (access) ? 1 << 4 : 0) | \
+	 (5 & (access) ? 1 << 5 : 0) | \
+	 (6 & (access) ? 1 << 6 : 0) | \
+	 (7 & (access) ? 1 << 7 : 0))
 
 static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 {
 	unsigned byte;
 
-	const u8 x = BYTE_MASK(ACC_EXEC_MASK);
-	const u8 w = BYTE_MASK(ACC_WRITE_MASK);
-	const u8 u = BYTE_MASK(ACC_USER_MASK);
+	const u8 x = ACC_BITS_MASK(ACC_EXEC_MASK);
+	const u8 w = ACC_BITS_MASK(ACC_WRITE_MASK);
+	const u8 u = ACC_BITS_MASK(ACC_USER_MASK);
 
 	bool cr4_smep = is_cr4_smep(mmu);
 	bool cr4_smap = is_cr4_smap(mmu);
 	bool cr0_wp = is_cr0_wp(mmu);
 	bool efer_nx = is_efer_nx(mmu);
 
+	/*
+	 * In hardware, page fault error codes are generated (as the name
+	 * suggests) on any kind of page fault.  permission_fault() and
+	 * paging_tmpl.h already use the same bits after a successful page
+	 * table walk, to indicate the kind of access being performed.
+	 *
+	 * However, PFERR_PRESENT_MASK and PFERR_RSVD_MASK are never set here,
+	 * exactly because the page walk is successful.  PFERR_PRESENT_MASK is
+	 * removed by the shift, while PFERR_RSVD_MASK is repurposed in
+	 * permission_fault() to indicate accesses that are *not* subject to
+	 * SMAP restrictions.
+	 */
 	for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) {
 		unsigned pfec = byte << 1;
 
@@ -5598,10 +5622,9 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 			 *   - The access is supervisor mode
 			 *   - If implicit supervisor access or X86_EFLAGS_AC is clear
 			 *
-			 * Here, we cover the first four conditions.
-			 * The fifth is computed dynamically in permission_fault();
-			 * PFERR_RSVD_MASK bit will be set in PFEC if the access is
-			 * *not* subject to SMAP restrictions.
+			 * Here, we cover the first four conditions.  The fifth
+			 * is computed dynamically in permission_fault() and
+			 * communicated by setting PFERR_RSVD_MASK.
 			 */
 			if (cr4_smap)
 				smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf;
-- 
2.52.0

Re: [PATCH 07/28] KVM: x86/mmu: rename and clarify BYTE_MASK

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> The BYTE_MASK macro is the central point of the black magic
> in update_permission_bitmask().  Rename it to something
> that relates to how it is used, and add a comment explaining
> how it works.
> 
> Using shifts instead of powers of two was actually suggested by
> David Hildenbrand back in 2017 for clarity[1] but I evidently
> forgot his suggestion when applying to kvm.git.

Never underestimate your love for decimal-based bitmasks :-)

>  static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
>  {
>  	unsigned byte;

Rename this as well?  It's "fine" here, but it gets quite awkward when
"KVM: x86/mmu: introduce ACC_READ_MASK" makes permissions[] an array of shorts,
not bytes.

No idea what to call it...

[PATCH 08/28] KVM: x86/mmu: separate more EPT/non-EPT permission_fault()

[Paolo Bonzini]

Move more of EPT handling entirely in the existing "if (!ept)"
conditional.  Use a new "rf" variable instead of uf for read permissions
for clarity.

Merge smepf and ff into a single variable because EPT's "SMEP" (actually
MBEC) is defined differently and does not need smepf.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/mmu.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 70fd6868a555..8bbda4684338 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5584,24 +5584,28 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 		 * that causes a fault with the given PFEC.
 		 */
 
+		/* Faults from reads to non-readable pages */
+		u8 rf = 0;
 		/* Faults from writes to non-writable pages */
 		u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0;
 		/* Faults from user mode accesses to supervisor pages */
-		u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
-		/* Faults from fetches of non-executable pages*/
-		u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0;
-		/* Faults from kernel mode fetches of user pages */
-		u8 smepf = 0;
+		u8 uf = 0;
+		/* Faults from fetches of non-executable pages */
+		u8 ff = 0;
 		/* Faults from kernel mode accesses of user pages */
 		u8 smapf = 0;
 
-		if (!ept) {
+		if (ept) {
+			rf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
+			ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
+		} else {
 			/* Faults from kernel mode accesses to user pages */
 			u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
 
-			/* Not really needed: !nx will cause pte.nx to fault */
-			if (!efer_nx)
-				ff = 0;
+			uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
+
+			if (efer_nx)
+				ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
 
 			/* Allow supervisor writes if !cr0.wp */
 			if (!cr0_wp)
@@ -5609,7 +5613,7 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 
 			/* Disallow supervisor fetches of user code if cr4.smep */
 			if (cr4_smep)
-				smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0;
+				ff |= (pfec & PFERR_FETCH_MASK) ? kf : 0;
 
 			/*
 			 * SMAP:kernel-mode data accesses from user-mode
@@ -5630,7 +5634,7 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 				smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf;
 		}
 
-		mmu->permissions[byte] = ff | uf | wf | smepf | smapf;
+		mmu->permissions[byte] = ff | uf | wf | rf | smapf;
 	}
 }
 
-- 
2.52.0

Re: [PATCH 08/28] KVM: x86/mmu: separate more EPT/non-EPT permission_fault()

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> -		if (!ept) {
> +		if (ept) {
> +			rf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
> +			ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
> +		} else {
>  			/* Faults from kernel mode accesses to user pages */
>  			u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
>  
> -			/* Not really needed: !nx will cause pte.nx to fault */
> -			if (!efer_nx)
> -				ff = 0;
> +			uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
> +
> +			if (efer_nx)
> +				ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;

Uber nit, probably makes sense to do:

				ff |= (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;

so that the ordering between efer_nx and cr4_smep doesn't matter.

If you end up doing fixup, this patch really should use (u8) instead (u16), and
then convert everything in "KVM: x86/mmu: introduce ACC_READ_MASK".  Doesn't
impact functionality, but it looks odd.

>  			/* Allow supervisor writes if !cr0.wp */
>  			if (!cr0_wp)

[PATCH 09/28] KVM: x86/mmu: introduce ACC_READ_MASK

[Paolo Bonzini]

Read permissions so far were only needed for EPT, which does not need
ACC_USER_MASK.  Therefore, for EPT page tables ACC_USER_MASK was repurposed
as a read permission bit.

In order to implement nested MBEC, EPT will genuinely have four kinds of
accesses, and there will be no room for such hacks; bite the bullet at
last, enlarging ACC_ALL to four bits and permissions[] to 2^4 bits (u16).

The new code does not enforce that the XWR bits on non-execonly processors
have their R bit set, even when running nested: none of the shadow_*_mask
values have bit 0 set, and make_spte() genuinely relies on ACC_READ_MASK
being requested!  This works because, if execonly is not supported by the
processor, shadow EPT will generate an EPT misconfig vmexit if the XWR
bits represent a non-readable page, and therefore the pte_access argument
to make_spte() will also always have ACC_READ_MASK set.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/kvm_host.h | 12 +++++-----
 arch/x86/kvm/mmu.h              |  2 +-
 arch/x86/kvm/mmu/mmu.c          | 41 ++++++++++++++++++++-------------
 arch/x86/kvm/mmu/mmutrace.h     |  3 ++-
 arch/x86/kvm/mmu/paging_tmpl.h  | 35 +++++++++++++++++-----------
 arch/x86/kvm/mmu/spte.c         | 18 ++++++---------
 arch/x86/kvm/mmu/spte.h         |  5 ++--
 arch/x86/kvm/vmx/capabilities.h |  5 ----
 arch/x86/kvm/vmx/common.h       |  5 +---
 arch/x86/kvm/vmx/vmx.c          |  3 +--
 10 files changed, 67 insertions(+), 62 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c470e40a00aa..8f2a1b915df9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -328,11 +328,11 @@ struct kvm_kernel_irq_routing_entry;
  * the number of unique SPs that can theoretically be created is 2^n, where n
  * is the number of bits that are used to compute the role.
  *
- * But, even though there are 20 bits in the mask below, not all combinations
+ * But, even though there are 21 bits in the mask below, not all combinations
  * of modes and flags are possible:
  *
  *   - invalid shadow pages are not accounted, mirror pages are not shadowed,
- *     so the bits are effectively 18.
+ *     so the bits are effectively 19.
  *
  *   - quadrant will only be used if has_4_byte_gpte=1 (non-PAE paging);
  *     execonly and ad_disabled are only used for nested EPT which has
@@ -347,7 +347,7 @@ struct kvm_kernel_irq_routing_entry;
  *     cr0_wp=0, therefore these three bits only give rise to 5 possibilities.
  *
  * Therefore, the maximum number of possible upper-level shadow pages for a
- * single gfn is a bit less than 2^13.
+ * single gfn is a bit less than 2^14.
  */
 union kvm_mmu_page_role {
 	u32 word;
@@ -356,7 +356,7 @@ union kvm_mmu_page_role {
 		unsigned has_4_byte_gpte:1;
 		unsigned quadrant:2;
 		unsigned direct:1;
-		unsigned access:3;
+		unsigned access:4;
 		unsigned invalid:1;
 		unsigned efer_nx:1;
 		unsigned cr0_wp:1;
@@ -366,7 +366,7 @@ union kvm_mmu_page_role {
 		unsigned guest_mode:1;
 		unsigned passthrough:1;
 		unsigned is_mirror:1;
-		unsigned :4;
+		unsigned:3;
 
 		/*
 		 * This is left at the top of the word so that
@@ -492,7 +492,7 @@ struct kvm_mmu {
 	 * Byte index: page fault error code [4:1]
 	 * Bit index: pte permissions in ACC_* format
 	 */
-	u8 permissions[16];
+	u16 permissions[16];
 
 	u64 *pae_root;
 	u64 *pml4_root;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 830f46145692..23f37535c0ce 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -81,7 +81,7 @@ u8 kvm_mmu_get_max_tdp_level(void);
 void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask);
 void kvm_mmu_set_mmio_spte_value(struct kvm *kvm, u64 mmio_value);
 void kvm_mmu_set_me_spte_mask(u64 me_value, u64 me_mask);
-void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only);
+void kvm_mmu_set_ept_masks(bool has_ad_bits);
 
 void kvm_init_mmu(struct kvm_vcpu *vcpu);
 void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8bbda4684338..fc1b17e22ea2 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2033,7 +2033,7 @@ static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 	 */
 	const union kvm_mmu_page_role sync_role_ign = {
 		.level = 0xf,
-		.access = 0x7,
+		.access = ACC_ALL,
 		.quadrant = 0x3,
 		.passthrough = 0x1,
 	};
@@ -5539,7 +5539,7 @@ reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly)
  * update_permission_bitmask() builds what is effectively a
  * two-dimensional array of bools.  The second dimension is
  * provided by individual bits of permissions[pfec >> 1], and
- * logical &, | and ~ operations operate on all the 8 possible
+ * logical &, | and ~ operations operate on all the 16 possible
  * combinations of ACC_* bits.
  */
 #define ACC_BITS_MASK(access) \
@@ -5549,15 +5549,23 @@ reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly)
 	 (4 & (access) ? 1 << 4 : 0) | \
 	 (5 & (access) ? 1 << 5 : 0) | \
 	 (6 & (access) ? 1 << 6 : 0) | \
-	 (7 & (access) ? 1 << 7 : 0))
+	 (7 & (access) ? 1 << 7 : 0) | \
+	 (8 & (access) ? 1 << 8 : 0) | \
+	 (9 & (access) ? 1 << 9 : 0) | \
+	 (10 & (access) ? 1 << 10 : 0) | \
+	 (11 & (access) ? 1 << 11 : 0) | \
+	 (12 & (access) ? 1 << 12 : 0) | \
+	 (13 & (access) ? 1 << 13 : 0) | \
+	 (14 & (access) ? 1 << 14 : 0) | \
+	 (15 & (access) ? 1 << 15 : 0))
 
 static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 {
 	unsigned byte;
 
-	const u8 x = ACC_BITS_MASK(ACC_EXEC_MASK);
-	const u8 w = ACC_BITS_MASK(ACC_WRITE_MASK);
-	const u8 u = ACC_BITS_MASK(ACC_USER_MASK);
+	const u16 x = ACC_BITS_MASK(ACC_EXEC_MASK);
+	const u16 w = ACC_BITS_MASK(ACC_WRITE_MASK);
+	const u16 r = ACC_BITS_MASK(ACC_READ_MASK);
 
 	bool cr4_smep = is_cr4_smep(mmu);
 	bool cr4_smap = is_cr4_smap(mmu);
@@ -5580,29 +5588,30 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 		unsigned pfec = byte << 1;
 
 		/*
-		 * Each "*f" variable has a 1 bit for each UWX value
+		 * Each "*f" variable has a 1 bit for each ACC_* combo
 		 * that causes a fault with the given PFEC.
 		 */
 
 		/* Faults from reads to non-readable pages */
-		u8 rf = 0;
+		u16 rf = (pfec & (PFERR_WRITE_MASK|PFERR_FETCH_MASK)) ? 0 : (u16)~r;
 		/* Faults from writes to non-writable pages */
-		u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0;
+		u16 wf = (pfec & PFERR_WRITE_MASK) ? (u16)~w : 0;
 		/* Faults from user mode accesses to supervisor pages */
-		u8 uf = 0;
+		u16 uf = 0;
 		/* Faults from fetches of non-executable pages */
-		u8 ff = 0;
+		u16 ff = 0;
 		/* Faults from kernel mode accesses of user pages */
-		u8 smapf = 0;
+		u16 smapf = 0;
 
 		if (ept) {
-			rf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
 			ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
 		} else {
-			/* Faults from kernel mode accesses to user pages */
-			u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
+			const u16 u = ACC_BITS_MASK(ACC_USER_MASK);
 
-			uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0;
+			/* Faults from kernel mode accesses to user pages */
+			u16 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
+
+			uf = (pfec & PFERR_USER_MASK) ? (u16)~u : 0;
 
 			if (efer_nx)
 				ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h
index 764e3015d021..dcfdfedfc4e9 100644
--- a/arch/x86/kvm/mmu/mmutrace.h
+++ b/arch/x86/kvm/mmu/mmutrace.h
@@ -25,7 +25,8 @@
 #define KVM_MMU_PAGE_PRINTK() ({				        \
 	const char *saved_ptr = trace_seq_buffer_ptr(p);		\
 	static const char *access_str[] = {			        \
-		"---", "--x", "w--", "w-x", "-u-", "-ux", "wu-", "wux"  \
+		"----", "r---", "-w--", "rw--", "--u-", "r-u-", "-wu-", "rwu-", \
+		"---x", "r--x", "-w-x", "rw-x", "--ux", "r-ux", "-wux", "rwux"	\
 	};							        \
 	union kvm_mmu_page_role role;				        \
 								        \
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 901cd2bd40b8..fb1b5d8b23e5 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -170,25 +170,24 @@ static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
 	return true;
 }
 
-/*
- * For PTTYPE_EPT, a page table can be executable but not readable
- * on supported processors. Therefore, set_spte does not automatically
- * set bit 0 if execute only is supported. Here, we repurpose ACC_USER_MASK
- * to signify readability since it isn't used in the EPT case
- */
 static inline unsigned FNAME(gpte_access)(u64 gpte)
 {
 	unsigned access;
 #if PTTYPE == PTTYPE_EPT
 	access = ((gpte & VMX_EPT_WRITABLE_MASK) ? ACC_WRITE_MASK : 0) |
 		((gpte & VMX_EPT_EXECUTABLE_MASK) ? ACC_EXEC_MASK : 0) |
-		((gpte & VMX_EPT_READABLE_MASK) ? ACC_USER_MASK : 0);
+		((gpte & VMX_EPT_READABLE_MASK) ? ACC_READ_MASK : 0);
 #else
-	BUILD_BUG_ON(ACC_EXEC_MASK != PT_PRESENT_MASK);
-	BUILD_BUG_ON(ACC_EXEC_MASK != 1);
+	/*
+	 * P is set here, so the page is always readable and W/U/!NX represent
+	 * allowed accesses.
+	 */
+	BUILD_BUG_ON(ACC_READ_MASK != PT_PRESENT_MASK);
+	BUILD_BUG_ON(ACC_WRITE_MASK != PT_WRITABLE_MASK);
+	BUILD_BUG_ON(ACC_USER_MASK != PT_USER_MASK);
+	BUILD_BUG_ON(ACC_EXEC_MASK & (PT_WRITABLE_MASK | PT_USER_MASK | PT_PRESENT_MASK));
 	access = gpte & (PT_WRITABLE_MASK | PT_USER_MASK | PT_PRESENT_MASK);
-	/* Combine NX with P (which is set here) to get ACC_EXEC_MASK.  */
-	access ^= (gpte >> PT64_NX_SHIFT);
+	access |= gpte & PT64_NX_MASK ? 0 : ACC_EXEC_MASK;
 #endif
 
 	return access;
@@ -501,10 +500,18 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 
 		if (write_fault)
 			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_WRITE;
-		if (user_fault)
-			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_READ;
-		if (fetch_fault)
+		else if (fetch_fault)
 			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_INSTR;
+		else
+			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_READ;
+
+		/*
+		 * Accesses to guest paging structures are either "reads" or
+		 * "read+write" accesses, so consider them the latter if write_fault
+		 * is true.
+		 */
+		if (access & PFERR_GUEST_PAGE_MASK)
+			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_READ;
 
 		/*
 		 * Note, pte_access holds the raw RWX bits from the EPTE, not
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index e9dc0ae44274..7b5f118ae211 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -194,12 +194,6 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 	int is_host_mmio = -1;
 	bool wrprot = false;
 
-	/*
-	 * For the EPT case, shadow_present_mask has no RWX bits set if
-	 * exec-only page table entries are supported.  In that case,
-	 * ACC_USER_MASK and shadow_user_mask are used to represent
-	 * read access.  See FNAME(gpte_access) in paging_tmpl.h.
-	 */
 	WARN_ON_ONCE((pte_access | shadow_present_mask) == SHADOW_NONPRESENT_VALUE);
 
 	if (sp->role.ad_disabled)
@@ -228,6 +222,9 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 		pte_access &= ~ACC_EXEC_MASK;
 	}
 
+	if (pte_access & ACC_READ_MASK)
+		spte |= PT_PRESENT_MASK; /* or VMX_EPT_READABLE_MASK */
+
 	if (pte_access & ACC_EXEC_MASK)
 		spte |= shadow_x_mask;
 	else
@@ -391,6 +388,7 @@ u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled)
 	u64 spte = SPTE_MMU_PRESENT_MASK;
 
 	spte |= __pa(child_pt) | shadow_present_mask | PT_WRITABLE_MASK |
+		PT_PRESENT_MASK /* or VMX_EPT_READABLE_MASK */ |
 		shadow_user_mask | shadow_x_mask | shadow_me_value;
 
 	if (ad_disabled)
@@ -491,18 +489,16 @@ void kvm_mmu_set_me_spte_mask(u64 me_value, u64 me_mask)
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_set_me_spte_mask);
 
-void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only)
+void kvm_mmu_set_ept_masks(bool has_ad_bits)
 {
 	kvm_ad_enabled		= has_ad_bits;
 
-	shadow_user_mask	= VMX_EPT_READABLE_MASK;
+	shadow_user_mask	= 0;
 	shadow_accessed_mask	= VMX_EPT_ACCESS_BIT;
 	shadow_dirty_mask	= VMX_EPT_DIRTY_BIT;
 	shadow_nx_mask		= 0ull;
 	shadow_x_mask		= VMX_EPT_EXECUTABLE_MASK;
-	/* VMX_EPT_SUPPRESS_VE_BIT is needed for W or X violation. */
-	shadow_present_mask	=
-		(has_exec_only ? 0ull : VMX_EPT_READABLE_MASK) | VMX_EPT_SUPPRESS_VE_BIT;
+	shadow_present_mask	= VMX_EPT_SUPPRESS_VE_BIT;
 
 	shadow_acc_track_mask	= VMX_EPT_RWX_MASK;
 	shadow_host_writable_mask = EPT_SPTE_HOST_WRITABLE;
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index bc02a2e89a31..121bfb2217e8 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -52,10 +52,11 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
 #define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
 #endif
 
-#define ACC_EXEC_MASK    1
+#define ACC_READ_MASK    PT_PRESENT_MASK
 #define ACC_WRITE_MASK   PT_WRITABLE_MASK
 #define ACC_USER_MASK    PT_USER_MASK
-#define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
+#define ACC_EXEC_MASK    8
+#define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK | ACC_READ_MASK)
 
 #define SPTE_LEVEL_BITS			9
 #define SPTE_LEVEL_SHIFT(level)		__PT_LEVEL_SHIFT(level, SPTE_LEVEL_BITS)
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 56cacc06225e..7e59eb0f41bb 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -300,11 +300,6 @@ static inline bool cpu_has_vmx_flexpriority(void)
 		cpu_has_vmx_virtualize_apic_accesses();
 }
 
-static inline bool cpu_has_vmx_ept_execute_only(void)
-{
-	return vmx_capability.ept & VMX_EPT_EXECUTE_ONLY_BIT;
-}
-
 static inline bool cpu_has_vmx_ept_4levels(void)
 {
 	return vmx_capability.ept & VMX_EPT_PAGE_WALK_4_BIT;
diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index adf925500b9e..1afbf272efae 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -85,11 +85,8 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
 {
 	u64 error_code;
 
-	/* Is it a read fault? */
-	error_code = (exit_qualification & EPT_VIOLATION_ACC_READ)
-		     ? PFERR_USER_MASK : 0;
 	/* Is it a write fault? */
-	error_code |= (exit_qualification & EPT_VIOLATION_ACC_WRITE)
+	error_code = (exit_qualification & EPT_VIOLATION_ACC_WRITE)
 		      ? PFERR_WRITE_MASK : 0;
 	/* Is it a fetch fault? */
 	error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a29896a9ef14..337bbfecc021 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8683,8 +8683,7 @@ __init int vmx_hardware_setup(void)
 	set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
 
 	if (enable_ept)
-		kvm_mmu_set_ept_masks(enable_ept_ad_bits,
-				      cpu_has_vmx_ept_execute_only());
+		kvm_mmu_set_ept_masks(enable_ept_ad_bits);
 	else
 		vt_x86_ops.get_mt_mask = NULL;
 
-- 
2.52.0

[PATCH 10/28] KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa

[Paolo Bonzini]

The XS/XU bit for EPT are only applied to final accesses, and use the
U bit from the page walk itself.  While strictly speaking not necessary
(any value of PFERR_USER_MASK would be the same for page table accesses,
because they're reads and writes only), it is clearer and less hackish
to only apply MBEC to PFERR_GUEST_FINAL_MASK.  Allow kvm-intel.ko to
distinguish the two cases.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/hyperv.c          | 3 ++-
 arch/x86/kvm/mmu/mmu.c         | 3 ++-
 arch/x86/kvm/mmu/paging_tmpl.h | 7 +++++--
 arch/x86/kvm/x86.c             | 3 ++-
 4 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 9b140bbdc1d8..cf9dd565b894 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2041,7 +2041,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 	 * read with kvm_read_guest().
 	 */
 	if (!hc->fast && is_guest_mode(vcpu)) {
-		hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa, 0, NULL);
+		hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa,
+					PFERR_GUEST_FINAL_MASK, NULL);
 		if (unlikely(hc->ingpa == INVALID_GPA))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
 	}
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index fc1b17e22ea2..0fc362508a19 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4348,7 +4348,8 @@ static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 {
 	if (exception)
 		exception->error_code = 0;
-	return kvm_translate_gpa(vcpu, mmu, vaddr, access, exception);
+	return kvm_translate_gpa(vcpu, mmu, vaddr, access | PFERR_GUEST_FINAL_MASK,
+				 exception);
 }
 
 static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index fb1b5d8b23e5..567f8b77ffe0 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -376,7 +376,8 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 		walker->pte_gpa[walker->level - 1] = pte_gpa;
 
 		real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(table_gfn),
-					     nested_access, &walker->fault);
+					     nested_access | PFERR_GUEST_PAGE_MASK,
+					     &walker->fault);
 
 		/*
 		 * FIXME: This can happen if emulation (for of an INS/OUTS
@@ -444,7 +445,9 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 		gfn += pse36_gfn_delta(pte);
 #endif
 
-	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn), access, &walker->fault);
+	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn),
+				     access | PFERR_GUEST_FINAL_MASK,
+				     &walker->fault);
 	if (real_gpa == INVALID_GPA)
 		return 0;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0a1b63c63d1a..ef1e3ae13887 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1072,7 +1072,8 @@ int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
 	 * to an L1 GPA.
 	 */
 	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(pdpt_gfn),
-				     PFERR_USER_MASK | PFERR_WRITE_MASK, NULL);
+				     PFERR_USER_MASK | PFERR_WRITE_MASK |
+				     PFERR_GUEST_PAGE_MASK, NULL);
 	if (real_gpa == INVALID_GPA)
 		return 0;
 
-- 
2.52.0

Re: [PATCH 10/28] KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa

[Sean Christopherson]

+Kevin and Yosry

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
>  static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
> diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
> index fb1b5d8b23e5..567f8b77ffe0 100644
> --- a/arch/x86/kvm/mmu/paging_tmpl.h
> +++ b/arch/x86/kvm/mmu/paging_tmpl.h
> @@ -376,7 +376,8 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
>  		walker->pte_gpa[walker->level - 1] = pte_gpa;
>  
>  		real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(table_gfn),
> -					     nested_access, &walker->fault);
> +					     nested_access | PFERR_GUEST_PAGE_MASK,
> +					     &walker->fault);
>  
>  		/*
>  		 * FIXME: This can happen if emulation (for of an INS/OUTS
> @@ -444,7 +445,9 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
>  		gfn += pse36_gfn_delta(pte);
>  #endif
>  
> -	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn), access, &walker->fault);
> +	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn),
> +				     access | PFERR_GUEST_FINAL_MASK,
> +				     &walker->fault);

Mostly a note to myself, we should make sure to land Kevin's fixes for synthesizing
the #NPF error code and EPT exit qualification in the same kernel (which I fully
plan on doing).  I'm just happy we all came up with the same annotations :-)

https://lore.kernel.org/all/20260313071033.4153209-3-chengkev@google.com

Re: [PATCH 10/28] KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa

[Paolo Bonzini]

On Thu, Apr 30, 2026 at 8:51 PM Sean Christopherson <seanjc@google.com> wrote:
>
> +Kevin and Yosry
>
> On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> >  static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
> > diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
> > index fb1b5d8b23e5..567f8b77ffe0 100644
> > --- a/arch/x86/kvm/mmu/paging_tmpl.h
> > +++ b/arch/x86/kvm/mmu/paging_tmpl.h
> > @@ -376,7 +376,8 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
> >               walker->pte_gpa[walker->level - 1] = pte_gpa;
> >
> >               real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(table_gfn),
> > -                                          nested_access, &walker->fault);
> > +                                          nested_access | PFERR_GUEST_PAGE_MASK,
> > +                                          &walker->fault);
> >
> >               /*
> >                * FIXME: This can happen if emulation (for of an INS/OUTS
> > @@ -444,7 +445,9 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
> >               gfn += pse36_gfn_delta(pte);
> >  #endif
> >
> > -     real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn), access, &walker->fault);
> > +     real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn),
> > +                                  access | PFERR_GUEST_FINAL_MASK,
> > +                                  &walker->fault);
>
> Mostly a note to myself, we should make sure to land Kevin's fixes for synthesizing
> the #NPF error code and EPT exit qualification in the same kernel (which I fully
> plan on doing).  I'm just happy we all came up with the same annotations :-)

Yes, passing down the exit qualification was yucky. I'll check what
needs to be done in Kevin's patches to support advanced EPT violation
info.

Paolo

>
> https://lore.kernel.org/all/20260313071033.4153209-3-chengkev@google.com
>

[PATCH 11/28] KVM: x86/mmu: pass pte_access for final nGPA->GPA walk

[Paolo Bonzini]

The XS/XU bit for EPT are only applied to final accesses, and use the
U bit from the page walk itself.  This is available in the page walker
as pte_access & ACC_USER_MASK but not available to translate_nested_gpa,
so pass it down.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/hyperv.c          |  2 +-
 arch/x86/kvm/mmu.h             | 15 ++++++++++++---
 arch/x86/kvm/mmu/mmu.c         |  8 +++++++-
 arch/x86/kvm/mmu/paging_tmpl.h |  4 ++--
 arch/x86/kvm/mmu/spte.h        |  6 ------
 arch/x86/kvm/x86.c             |  5 +++--
 6 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index cf9dd565b894..53688f7b76eb 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2042,7 +2042,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 	 */
 	if (!hc->fast && is_guest_mode(vcpu)) {
 		hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa,
-					PFERR_GUEST_FINAL_MASK, NULL);
+					PFERR_GUEST_FINAL_MASK, NULL, 0);
 		if (unlikely(hc->ingpa == INVALID_GPA))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
 	}
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 23f37535c0ce..635c2e5d8513 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -37,6 +37,12 @@ extern bool __read_mostly enable_mmio_caching;
 #define PT32_ROOT_LEVEL 2
 #define PT32E_ROOT_LEVEL 3
 
+#define ACC_READ_MASK    PT_PRESENT_MASK
+#define ACC_WRITE_MASK   PT_WRITABLE_MASK
+#define ACC_USER_MASK    PT_USER_MASK
+#define ACC_EXEC_MASK    8
+#define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK | ACC_READ_MASK)
+
 #define KVM_MMU_CR4_ROLE_BITS (X86_CR4_PSE | X86_CR4_PAE | X86_CR4_LA57 | \
 			       X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE)
 
@@ -289,16 +295,19 @@ static inline void kvm_update_page_stats(struct kvm *kvm, int level, int count)
 }
 
 gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception);
+			   struct x86_exception *exception,
+			   u64 pte_access);
 
 static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 				      struct kvm_mmu *mmu,
 				      gpa_t gpa, u64 access,
-				      struct x86_exception *exception)
+				      struct x86_exception *exception,
+				      u64 pte_access)
 {
 	if (mmu != &vcpu->arch.nested_mmu)
 		return gpa;
-	return translate_nested_gpa(vcpu, gpa, access, exception);
+	return translate_nested_gpa(vcpu, gpa, access, exception,
+				    pte_access);
 }
 
 static inline bool kvm_has_mirrored_tdp(const struct kvm *kvm)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0fc362508a19..88d0ff95fc8c 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4348,8 +4348,14 @@ static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 {
 	if (exception)
 		exception->error_code = 0;
+	/*
+	 * EPT MBEC uses the effective access bits from the PTE to distinguish
+	 * user and supervisor accesses, and treats every linear address as a
+	 * user-mode address if CR0.PG=0.  Therefore *include* ACC_USER_MASK in
+	 * the last argument to kvm_translate_gpa (which NPT does not use).
+	 */
 	return kvm_translate_gpa(vcpu, mmu, vaddr, access | PFERR_GUEST_FINAL_MASK,
-				 exception);
+				 exception, ACC_ALL);
 }
 
 static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 567f8b77ffe0..8dd9d510fc34 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -377,7 +377,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 
 		real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(table_gfn),
 					     nested_access | PFERR_GUEST_PAGE_MASK,
-					     &walker->fault);
+					     &walker->fault, 0);
 
 		/*
 		 * FIXME: This can happen if emulation (for of an INS/OUTS
@@ -447,7 +447,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 
 	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn),
 				     access | PFERR_GUEST_FINAL_MASK,
-				     &walker->fault);
+				     &walker->fault, walker->pte_access);
 	if (real_gpa == INVALID_GPA)
 		return 0;
 
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 121bfb2217e8..8a4c09c5cdbf 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -52,12 +52,6 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
 #define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
 #endif
 
-#define ACC_READ_MASK    PT_PRESENT_MASK
-#define ACC_WRITE_MASK   PT_WRITABLE_MASK
-#define ACC_USER_MASK    PT_USER_MASK
-#define ACC_EXEC_MASK    8
-#define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK | ACC_READ_MASK)
-
 #define SPTE_LEVEL_BITS			9
 #define SPTE_LEVEL_SHIFT(level)		__PT_LEVEL_SHIFT(level, SPTE_LEVEL_BITS)
 #define SPTE_INDEX(address, level)	__PT_INDEX(address, level, SPTE_LEVEL_BITS)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ef1e3ae13887..67979b7de5d6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1073,7 +1073,7 @@ int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
 	 */
 	real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(pdpt_gfn),
 				     PFERR_USER_MASK | PFERR_WRITE_MASK |
-				     PFERR_GUEST_PAGE_MASK, NULL);
+				     PFERR_GUEST_PAGE_MASK, NULL, 0);
 	if (real_gpa == INVALID_GPA)
 		return 0;
 
@@ -7849,7 +7849,8 @@ void kvm_get_segment(struct kvm_vcpu *vcpu,
 }
 
 gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception)
+			   struct x86_exception *exception,
+			   u64 pte_access)
 {
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
 	gpa_t t_gpa;
-- 
2.52.0

[PATCH 12/28] KVM: x86: make translate_nested_gpa vendor-specific

[Paolo Bonzini]

EPT and NPT have different rules for passing PFERR_USER_MASK to the
nested page table walk.  In particular, for final addresses EPT
uses the U bit of the guest (nGVA->nGPA) walk.

While at it, remove PFERR_USER_MASK from the VMX version of the
function, since it is actually ignored by the tables that
update_permission_bitmask() generates for EPT.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  4 ++++
 arch/x86/kvm/hyperv.c           |  3 ++-
 arch/x86/kvm/mmu.h              |  9 +++------
 arch/x86/kvm/svm/nested.c       | 15 +++++++++++++++
 arch/x86/kvm/vmx/nested.c       | 12 ++++++++++++
 arch/x86/kvm/x86.c              | 16 ----------------
 6 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8f2a1b915df9..62dc782b2dd3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2010,6 +2010,10 @@ struct kvm_x86_nested_ops {
 			 struct kvm_nested_state *kvm_state);
 	bool (*get_nested_state_pages)(struct kvm_vcpu *vcpu);
 	int (*write_log_dirty)(struct kvm_vcpu *vcpu, gpa_t l2_gpa);
+	gpa_t (*translate_nested_gpa)(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access);
 
 	int (*enable_evmcs)(struct kvm_vcpu *vcpu,
 			    uint16_t *vmcs_version);
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 53688f7b76eb..f35fae3a7b3d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2041,7 +2041,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 	 * read with kvm_read_guest().
 	 */
 	if (!hc->fast && is_guest_mode(vcpu)) {
-		hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa,
+		hc->ingpa = kvm_x86_ops.nested_ops->translate_nested_gpa(
+					vcpu, hc->ingpa,
 					PFERR_GUEST_FINAL_MASK, NULL, 0);
 		if (unlikely(hc->ingpa == INVALID_GPA))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 635c2e5d8513..63be5c5efed9 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -294,10 +294,6 @@ static inline void kvm_update_page_stats(struct kvm *kvm, int level, int count)
 	atomic64_add(count, &kvm->stat.pages[level - 1]);
 }
 
-gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception,
-			   u64 pte_access);
-
 static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 				      struct kvm_mmu *mmu,
 				      gpa_t gpa, u64 access,
@@ -306,8 +302,9 @@ static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 {
 	if (mmu != &vcpu->arch.nested_mmu)
 		return gpa;
-	return translate_nested_gpa(vcpu, gpa, access, exception,
-				    pte_access);
+	return kvm_x86_ops.nested_ops->translate_nested_gpa(vcpu, gpa, access,
+							    exception,
+							    pte_access);
 }
 
 static inline bool kvm_has_mirrored_tdp(const struct kvm *kvm)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 961804df5f45..df232153eb24 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -2071,8 +2071,23 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static gpa_t svm_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access)
+{
+	struct kvm_mmu *mmu = vcpu->arch.mmu;
+
+	BUG_ON(!mmu_is_nested(vcpu));
+
+	/* NPT walks are always user-walks */
+	access |= PFERR_USER_MASK;
+	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
+}
+
 struct kvm_x86_nested_ops svm_nested_ops = {
 	.leave_nested = svm_leave_nested,
+	.translate_nested_gpa = svm_translate_nested_gpa,
 	.is_exception_vmexit = nested_svm_is_exception_vmexit,
 	.check_events = svm_check_nested_events,
 	.triple_fault = nested_svm_triple_fault,
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3fe88f29be7a..cd1924c6e075 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7438,8 +7438,20 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
 	return 0;
 }
 
+static gpa_t vmx_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access)
+{
+	struct kvm_mmu *mmu = vcpu->arch.mmu;
+
+	BUG_ON(!mmu_is_nested(vcpu));
+	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
+}
+
 struct kvm_x86_nested_ops vmx_nested_ops = {
 	.leave_nested = vmx_leave_nested,
+	.translate_nested_gpa = vmx_translate_nested_gpa,
 	.is_exception_vmexit = nested_vmx_is_exception_vmexit,
 	.check_events = vmx_check_nested_events,
 	.has_events = vmx_has_nested_events,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 67979b7de5d6..7c6942afae81 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7848,22 +7848,6 @@ void kvm_get_segment(struct kvm_vcpu *vcpu,
 	kvm_x86_call(get_segment)(vcpu, var, seg);
 }
 
-gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception,
-			   u64 pte_access)
-{
-	struct kvm_mmu *mmu = vcpu->arch.mmu;
-	gpa_t t_gpa;
-
-	BUG_ON(!mmu_is_nested(vcpu));
-
-	/* NPT walks are always user-walks */
-	access |= PFERR_USER_MASK;
-	t_gpa  = mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
-
-	return t_gpa;
-}
-
 gpa_t kvm_mmu_gva_to_gpa_read(struct kvm_vcpu *vcpu, gva_t gva,
 			      struct x86_exception *exception)
 {
-- 
2.52.0

Re: [PATCH 12/28] KVM: x86: make translate_nested_gpa vendor-specific

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> EPT and NPT have different rules for passing PFERR_USER_MASK to the
> nested page table walk.  In particular, for final addresses EPT
> uses the U bit of the guest (nGVA->nGPA) walk.
> 
> While at it, remove PFERR_USER_MASK from the VMX version of the
> function, since it is actually ignored by the tables that
> update_permission_bitmask() generates for EPT.
> 
> Tested-by: David Riley <d.riley@proxmox.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---

...

>  struct kvm_x86_nested_ops svm_nested_ops = {
>  	.leave_nested = svm_leave_nested,
> +	.translate_nested_gpa = svm_translate_nested_gpa,
>  	.is_exception_vmexit = nested_svm_is_exception_vmexit,
>  	.check_events = svm_check_nested_events,
>  	.triple_fault = nested_svm_triple_fault,

Paolo, do you have any objection to adding static_call() support for nested_ops?
I vaguely recall you not wanting to do so.  But we're reaching the point where
quite a few callbacks are in relative hot paths.

Re: [PATCH 12/28] KVM: x86: make translate_nested_gpa vendor-specific

[Paolo Bonzini]

On Thu, Apr 30, 2026 at 8:53 PM Sean Christopherson <seanjc@google.com> wrote:
> >  struct kvm_x86_nested_ops svm_nested_ops = {
> >       .leave_nested = svm_leave_nested,
> > +     .translate_nested_gpa = svm_translate_nested_gpa,
> >       .is_exception_vmexit = nested_svm_is_exception_vmexit,
> >       .check_events = svm_check_nested_events,
> >       .triple_fault = nested_svm_triple_fault,
>
> Paolo, do you have any objection to adding static_call() support for nested_ops?
> I vaguely recall you not wanting to do so.  But we're reaching the point where
> quite a few callbacks are in relative hot paths.

No, I don't think I ever objected to it. In fact I do believe it's
slightly ugly.

Paolo

[PATCH 13/28] KVM: x86/mmu: split XS/XU bits for EPT

[Paolo Bonzini]

When EPT is in use, replace ACC_USER_MASK with ACC_USER_EXEC_MASK,
so that supervisor and user-mode execution can be controlled
independently (ACC_USER_MASK would not allow a setting similar to
XU=0 XS=1 W=1 R=1).

Replace shadow_x_mask with shadow_xs_mask/shadow_xu_mask, to allow
setting XS and XU bits separately in EPT entries.

Note that ACC_USER_EXEC_MASK is already set through ACC_ALL in
the kvm_mmu_page roles, but it does not propagate to the XU bit
because (for now) shadow_xs_mask == shadow_xu_mask.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu.h          |  3 +-
 arch/x86/kvm/mmu/mmu.c      |  2 +-
 arch/x86/kvm/mmu/mmutrace.h |  6 ++--
 arch/x86/kvm/mmu/spte.c     | 60 ++++++++++++++++++++++++++-----------
 arch/x86/kvm/mmu/spte.h     | 11 +++++--
 5 files changed, 58 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 63be5c5efed9..d8c13e43c2d7 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -39,7 +39,8 @@ extern bool __read_mostly enable_mmio_caching;
 
 #define ACC_READ_MASK    PT_PRESENT_MASK
 #define ACC_WRITE_MASK   PT_WRITABLE_MASK
-#define ACC_USER_MASK    PT_USER_MASK
+#define ACC_USER_MASK    PT_USER_MASK   /* non EPT */
+#define ACC_USER_EXEC_MASK ACC_USER_MASK /* EPT only */
 #define ACC_EXEC_MASK    8
 #define ACC_ALL          (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK | ACC_READ_MASK)
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 88d0ff95fc8c..617a3204a5e0 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5491,7 +5491,7 @@ static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu,
 static inline bool boot_cpu_is_amd(void)
 {
 	WARN_ON_ONCE(!tdp_enabled);
-	return shadow_x_mask == 0;
+	return shadow_xs_mask == 0;
 }
 
 /*
diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h
index dcfdfedfc4e9..3429c1413f42 100644
--- a/arch/x86/kvm/mmu/mmutrace.h
+++ b/arch/x86/kvm/mmu/mmutrace.h
@@ -357,8 +357,8 @@ TRACE_EVENT(
 		__entry->sptep = virt_to_phys(sptep);
 		__entry->level = level;
 		__entry->r = shadow_present_mask || (__entry->spte & PT_PRESENT_MASK);
-		__entry->x = is_executable_pte(__entry->spte);
-		__entry->u = shadow_user_mask ? !!(__entry->spte & shadow_user_mask) : -1;
+		__entry->x = (__entry->spte & (shadow_xs_mask | shadow_nx_mask)) == shadow_xs_mask;
+		__entry->u = !!(__entry->spte & (shadow_xu_mask | shadow_user_mask));
 	),
 
 	TP_printk("gfn %llx spte %llx (%s%s%s%s) level %d at %llx",
@@ -366,7 +366,7 @@ TRACE_EVENT(
 		  __entry->r ? "r" : "-",
 		  __entry->spte & PT_WRITABLE_MASK ? "w" : "-",
 		  __entry->x ? "x" : "-",
-		  __entry->u == -1 ? "" : (__entry->u ? "u" : "-"),
+		  __entry->u ? "u" : "-",
 		  __entry->level, __entry->sptep
 	)
 );
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 7b5f118ae211..4575dd77f854 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -29,8 +29,9 @@ bool __read_mostly kvm_ad_enabled;
 u64 __read_mostly shadow_host_writable_mask;
 u64 __read_mostly shadow_mmu_writable_mask;
 u64 __read_mostly shadow_nx_mask;
-u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */
 u64 __read_mostly shadow_user_mask;
+u64 __read_mostly shadow_xs_mask; /* mutual exclusive with nx_mask and user_mask */
+u64 __read_mostly shadow_xu_mask; /* mutual exclusive with nx_mask and user_mask */
 u64 __read_mostly shadow_accessed_mask;
 u64 __read_mostly shadow_dirty_mask;
 u64 __read_mostly shadow_mmio_value;
@@ -217,21 +218,26 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 	 * would tie make_spte() further to vCPU/MMU state, and add complexity
 	 * just to optimize a mode that is anything but performance critical.
 	 */
-	if (level > PG_LEVEL_4K && (pte_access & ACC_EXEC_MASK) &&
-	    is_nx_huge_page_enabled(vcpu->kvm)) {
+	if (level > PG_LEVEL_4K && is_nx_huge_page_enabled(vcpu->kvm)) {
 		pte_access &= ~ACC_EXEC_MASK;
+		if (shadow_xu_mask)
+			pte_access &= ~ACC_USER_EXEC_MASK;
 	}
 
 	if (pte_access & ACC_READ_MASK)
 		spte |= PT_PRESENT_MASK; /* or VMX_EPT_READABLE_MASK */
 
-	if (pte_access & ACC_EXEC_MASK)
-		spte |= shadow_x_mask;
-	else
-		spte |= shadow_nx_mask;
-
-	if (pte_access & ACC_USER_MASK)
-		spte |= shadow_user_mask;
+	if (shadow_nx_mask) {
+		if (!(pte_access & ACC_EXEC_MASK))
+			spte |= shadow_nx_mask;
+		if (pte_access & ACC_USER_MASK)
+			spte |= shadow_user_mask;
+	} else {
+		if (pte_access & ACC_EXEC_MASK)
+			spte |= shadow_xs_mask;
+		if (pte_access & ACC_USER_EXEC_MASK)
+			spte |= shadow_xu_mask;
+	}
 
 	if (level > PG_LEVEL_4K)
 		spte |= PT_PAGE_SIZE_MASK;
@@ -318,11 +324,13 @@ static u64 make_spte_executable(u64 spte, u8 access)
 {
 	u64 set, clear;
 
-	if (access & ACC_EXEC_MASK)
-		set = shadow_x_mask;
+	if (shadow_nx_mask)
+		set = (access & ACC_EXEC_MASK) ? 0 : shadow_nx_mask;
 	else
-		set = shadow_nx_mask;
-	clear = set ^ (shadow_nx_mask | shadow_x_mask);
+		set =
+			(access & ACC_EXEC_MASK ? shadow_xs_mask : 0) |
+			(access & ACC_USER_EXEC_MASK ? shadow_xu_mask : 0);
+	clear = set ^ (shadow_nx_mask | shadow_xs_mask | shadow_xu_mask);
 	return modify_spte_protections(spte, set, clear);
 }
 
@@ -389,7 +397,7 @@ u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled)
 
 	spte |= __pa(child_pt) | shadow_present_mask | PT_WRITABLE_MASK |
 		PT_PRESENT_MASK /* or VMX_EPT_READABLE_MASK */ |
-		shadow_user_mask | shadow_x_mask | shadow_me_value;
+		shadow_user_mask | shadow_xs_mask | shadow_xu_mask | shadow_me_value;
 
 	if (ad_disabled)
 		spte |= SPTE_TDP_AD_DISABLED;
@@ -497,7 +505,24 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits)
 	shadow_accessed_mask	= VMX_EPT_ACCESS_BIT;
 	shadow_dirty_mask	= VMX_EPT_DIRTY_BIT;
 	shadow_nx_mask		= 0ull;
-	shadow_x_mask		= VMX_EPT_EXECUTABLE_MASK;
+	shadow_xs_mask		= VMX_EPT_EXECUTABLE_MASK;
+
+	/*
+	 * The MMU always maps ACC_EXEC_MASK and ACC_USER_EXEC_MASK to the
+	 * XS and XU bits of shadow EPT entries, regardless of whether MBEC
+	 * is available on the host or enabled by the L1 hypervisor's EPTP.
+	 *
+	 * For the non-nested case, pages are mapped with ACC_EXEC_MASK
+	 * and ACC_USER_EXEC_MASK set in tandem, so XS == XU and the
+	 * host's MBEC setting does not matter.  On hardware without MBEC
+	 * the XU bit is reserved-as-ignored, and setting it does no harm.
+	 *
+	 * For nested EPT MBEC is not supported, but bit 10 of the gPTE has
+	 * no effect because (a) is_present_gpte() does not treat it as a
+	 * present bit, and (b) permission_fault() uses an mmu->permissions[]
+	 * array that effectively ignores ACC_USER_EXEC_MASK.
+	 */
+	shadow_xu_mask		= VMX_EPT_USER_EXECUTABLE_MASK;
 	shadow_present_mask	= VMX_EPT_SUPPRESS_VE_BIT;
 
 	shadow_acc_track_mask	= VMX_EPT_RWX_MASK;
@@ -548,7 +573,8 @@ void kvm_mmu_reset_all_pte_masks(void)
 	shadow_accessed_mask	= PT_ACCESSED_MASK;
 	shadow_dirty_mask	= PT_DIRTY_MASK;
 	shadow_nx_mask		= PT64_NX_MASK;
-	shadow_x_mask		= 0;
+	shadow_xs_mask		= 0;
+	shadow_xu_mask		= 0;
 	shadow_present_mask	= PT_PRESENT_MASK;
 
 	shadow_acc_track_mask	= 0;
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 8a4c09c5cdbf..0ed690f78e17 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -178,8 +178,9 @@ extern bool __read_mostly kvm_ad_enabled;
 extern u64 __read_mostly shadow_host_writable_mask;
 extern u64 __read_mostly shadow_mmu_writable_mask;
 extern u64 __read_mostly shadow_nx_mask;
-extern u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */
 extern u64 __read_mostly shadow_user_mask;
+extern u64 __read_mostly shadow_xs_mask; /* mutual exclusive with nx_mask and user_mask */
+extern u64 __read_mostly shadow_xu_mask; /* mutual exclusive with nx_mask and user_mask */
 extern u64 __read_mostly shadow_accessed_mask;
 extern u64 __read_mostly shadow_dirty_mask;
 extern u64 __read_mostly shadow_mmio_value;
@@ -357,7 +358,13 @@ static inline bool is_last_spte(u64 pte, int level)
 
 static inline bool is_executable_pte(u64 spte)
 {
-	return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask;
+	/*
+	 * For now, return true if either the XS or XU bit is set
+	 * This function is only used for fast_page_fault,
+	 * which never processes shadow EPT, and regular page
+	 * tables always have XS==XU.
+	 */
+	return (spte & (shadow_xs_mask | shadow_xu_mask | shadow_nx_mask)) != shadow_nx_mask;
 }
 
 static inline kvm_pfn_t spte_to_pfn(u64 pte)
-- 
2.52.0

[PATCH 14/28] KVM: x86/mmu: move cr4_smep to base role

[Paolo Bonzini]

Guest page tables can be reused independent of the value of CR4.SMEP
(at least if WP=1).  However, this is not true of EPT MBEC pages,
because presence of EPT entries is signaled by bits 0-2 when MBEC
is off, and bits 0-2 + bit 10 when MBEC is on.

In preparation for enabling MBEC, move cr4_smep to the base role.
This makes the smep_andnot_wp bit redundant, so remove it.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Documentation/virt/kvm/x86/mmu.rst | 10 ++++------
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    | 23 +++++++++++++++--------
 arch/x86/kvm/mmu/mmu.c             |  6 +++---
 4 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/Documentation/virt/kvm/x86/mmu.rst b/Documentation/virt/kvm/x86/mmu.rst
index 2b3b6d442302..666aa179601a 100644
--- a/Documentation/virt/kvm/x86/mmu.rst
+++ b/Documentation/virt/kvm/x86/mmu.rst
@@ -184,10 +184,8 @@ Shadow pages contain the following information:
     Contains the value of efer.nx for which the page is valid.
   role.cr0_wp:
     Contains the value of cr0.wp for which the page is valid.
-  role.smep_andnot_wp:
-    Contains the value of cr4.smep && !cr0.wp for which the page is valid
-    (pages for which this is true are different from other pages; see the
-    treatment of cr0.wp=0 below).
+  role.cr4_smep:
+    Contains the value of cr4.smep for which the page is valid.
   role.smap_andnot_wp:
     Contains the value of cr4.smap && !cr0.wp for which the page is valid
     (pages for which this is true are different from other pages; see the
@@ -435,8 +433,8 @@ from being written by the kernel after cr0.wp has changed to 1, we make
 the value of cr0.wp part of the page role.  This means that an spte created
 with one value of cr0.wp cannot be used when cr0.wp has a different value -
 it will simply be missed by the shadow page lookup code.  A similar issue
-exists when an spte created with cr0.wp=0 and cr4.smep=0 is used after
-changing cr4.smep to 1.  To avoid this, the value of !cr0.wp && cr4.smep
+exists when an spte created with cr0.wp=0 and cr4.smap=0 is used after
+changing cr4.smap to 1.  To avoid this, the value of !cr0.wp && cr4.smap
 is also made a part of the page role.
 
 Large pages
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 3776cf5382a2..e4fca997ec79 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -94,6 +94,7 @@ KVM_X86_OP_OPTIONAL(sync_pir_to_irr)
 KVM_X86_OP_OPTIONAL_RET0(set_tss_addr)
 KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
 KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
+KVM_X86_OP_OPTIONAL_RET0(tdp_has_smep)
 KVM_X86_OP(load_mmu_pgd)
 KVM_X86_OP_OPTIONAL(link_external_spt)
 KVM_X86_OP_OPTIONAL(set_external_spte)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 62dc782b2dd3..23a7ac8d7fbe 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -343,8 +343,8 @@ struct kvm_kernel_irq_routing_entry;
  *     paging has exactly one upper level, making level completely redundant
  *     when has_4_byte_gpte=1.
  *
- *   - on top of this, smep_andnot_wp and smap_andnot_wp are only set if
- *     cr0_wp=0, therefore these three bits only give rise to 5 possibilities.
+ *   - on top of this, smap_andnot_wp is only set if cr0_wp=0,
+ *     therefore these two bits only give rise to 3 possibilities.
  *
  * Therefore, the maximum number of possible upper-level shadow pages for a
  * single gfn is a bit less than 2^14.
@@ -360,12 +360,19 @@ union kvm_mmu_page_role {
 		unsigned invalid:1;
 		unsigned efer_nx:1;
 		unsigned cr0_wp:1;
-		unsigned smep_andnot_wp:1;
 		unsigned smap_andnot_wp:1;
 		unsigned ad_disabled:1;
 		unsigned guest_mode:1;
 		unsigned passthrough:1;
 		unsigned is_mirror:1;
+
+		/*
+		 * cr4_smep is also set for EPT MBEC.  Because it affects
+		 * which pages are considered non-present (bit 10 additionally
+		 * must be zero if MBEC is on) it has to be in the base role.
+		 */
+		unsigned cr4_smep:1;
+
 		unsigned:3;
 
 		/*
@@ -392,10 +399,10 @@ union kvm_mmu_page_role {
  * tables (because KVM doesn't support Protection Keys with shadow paging), and
  * CR0.PG, CR4.PAE, and CR4.PSE are indirectly reflected in role.level.
  *
- * Note, SMEP and SMAP are not redundant with sm*p_andnot_wp in the page role.
- * If CR0.WP=1, KVM can reuse shadow pages for the guest regardless of SMEP and
- * SMAP, but the MMU's permission checks for software walks need to be SMEP and
- * SMAP aware regardless of CR0.WP.
+ * Note, SMAP is not redundant with smap_andnot_wp in the page role.  If
+ * CR0.WP=1, KVM can reuse shadow pages for the guest regardless of SMAP,
+ * but the MMU's permission checks for software walks need to be SMAP
+ * aware regardless of CR0.WP.
  */
 union kvm_mmu_extended_role {
 	u32 word;
@@ -405,7 +412,6 @@ union kvm_mmu_extended_role {
 		unsigned int cr4_pse:1;
 		unsigned int cr4_pke:1;
 		unsigned int cr4_smap:1;
-		unsigned int cr4_smep:1;
 		unsigned int cr4_la57:1;
 		unsigned int efer_lma:1;
 	};
@@ -1887,6 +1893,7 @@ struct kvm_x86_ops {
 	int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
 	int (*set_identity_map_addr)(struct kvm *kvm, u64 ident_addr);
 	u8 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
+	bool (*tdp_has_smep)(struct kvm *kvm);
 
 	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 			     int root_level);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 617a3204a5e0..245a2e92793d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -227,7 +227,7 @@ static inline bool __maybe_unused is_##reg##_##name(struct kvm_mmu *mmu)	\
 }
 BUILD_MMU_ROLE_ACCESSOR(base, cr0, wp);
 BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, pse);
-BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, smep);
+BUILD_MMU_ROLE_ACCESSOR(base, cr4, smep);
 BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, smap);
 BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, pke);
 BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, la57);
@@ -5764,7 +5764,7 @@ static union kvm_cpu_role kvm_calc_cpu_role(struct kvm_vcpu *vcpu,
 
 	role.base.efer_nx = ____is_efer_nx(regs);
 	role.base.cr0_wp = ____is_cr0_wp(regs);
-	role.base.smep_andnot_wp = ____is_cr4_smep(regs) && !____is_cr0_wp(regs);
+	role.base.cr4_smep = ____is_cr4_smep(regs);
 	role.base.smap_andnot_wp = ____is_cr4_smap(regs) && !____is_cr0_wp(regs);
 	role.base.has_4_byte_gpte = !____is_cr4_pae(regs);
 
@@ -5776,7 +5776,6 @@ static union kvm_cpu_role kvm_calc_cpu_role(struct kvm_vcpu *vcpu,
 	else
 		role.base.level = PT32_ROOT_LEVEL;
 
-	role.ext.cr4_smep = ____is_cr4_smep(regs);
 	role.ext.cr4_smap = ____is_cr4_smap(regs);
 	role.ext.cr4_pse = ____is_cr4_pse(regs);
 
@@ -5835,6 +5834,7 @@ kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu,
 
 	role.access = ACC_ALL;
 	role.cr0_wp = true;
+	role.cr4_smep = kvm_x86_call(tdp_has_smep)(vcpu->kvm);
 	role.efer_nx = true;
 	role.smm = cpu_role.base.smm;
 	role.guest_mode = cpu_role.base.guest_mode;
-- 
2.52.0

[PATCH 15/28] KVM: VMX: enable use of MBEC

[Paolo Bonzini]

If available, set SECONDARY_EXEC_MODE_BASED_EPT_EXEC in the secondary
execution controls.

XS and XU are configured separately even if host does not support MBEC,
to avoid confusion where an L1 hypervisor sets bit 10 in its EPT
(knowing the non-MBEC hardware ignores it) but clears bit 2 to make the
page non-executable, and KVM sets the X bit via shadow_xu_mask.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/vmx.h      |  3 +++
 arch/x86/kvm/mmu.h              |  5 +++++
 arch/x86/kvm/mmu/spte.c         |  2 +-
 arch/x86/kvm/mmu/spte.h         |  5 +++--
 arch/x86/kvm/vmx/capabilities.h |  7 +++++++
 arch/x86/kvm/vmx/common.h       | 10 +++++-----
 arch/x86/kvm/vmx/main.c         |  9 +++++++++
 arch/x86/kvm/vmx/nested.c       |  1 +
 arch/x86/kvm/vmx/vmx.c          | 16 +++++++++++++++-
 arch/x86/kvm/vmx/vmx.h          |  1 +
 arch/x86/kvm/vmx/x86_ops.h      |  1 +
 11 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 2b30b921b375..54aa5be50df9 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -619,9 +619,12 @@ enum vm_entry_failure_code {
 #define EPT_VIOLATION_GVA_TRANSLATED	BIT(8)
 
 #define EPT_VIOLATION_RWX_TO_PROT(__epte) (((__epte) & VMX_EPT_RWX_MASK) << 3)
+#define EPT_VIOLATION_USER_EXEC_TO_PROT(__epte) (((__epte) & VMX_EPT_USER_EXECUTABLE_MASK) >> 4)
 
 static_assert(EPT_VIOLATION_RWX_TO_PROT(VMX_EPT_RWX_MASK) ==
 	      (EPT_VIOLATION_PROT_READ | EPT_VIOLATION_PROT_WRITE | EPT_VIOLATION_PROT_EXEC));
+static_assert(EPT_VIOLATION_USER_EXEC_TO_PROT(VMX_EPT_USER_EXECUTABLE_MASK) ==
+	      (EPT_VIOLATION_PROT_USER_EXEC));
 
 /*
  * Exit Qualifications for NOTIFY VM EXIT
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index d8c13e43c2d7..23bc5b18efd0 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -83,6 +83,11 @@ static inline gfn_t kvm_mmu_max_gfn(void)
 	return (1ULL << (max_gpa_bits - PAGE_SHIFT)) - 1;
 }
 
+static inline bool mmu_has_mbec(struct kvm_mmu *mmu)
+{
+	return mmu->root_role.cr4_smep;
+}
+
 u8 kvm_mmu_get_max_tdp_level(void);
 
 void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask);
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 4575dd77f854..09e6f494dcf4 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -525,7 +525,7 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits)
 	shadow_xu_mask		= VMX_EPT_USER_EXECUTABLE_MASK;
 	shadow_present_mask	= VMX_EPT_SUPPRESS_VE_BIT;
 
-	shadow_acc_track_mask	= VMX_EPT_RWX_MASK;
+	shadow_acc_track_mask	= VMX_EPT_RWX_MASK | VMX_EPT_USER_EXECUTABLE_MASK;
 	shadow_host_writable_mask = EPT_SPTE_HOST_WRITABLE;
 	shadow_mmu_writable_mask  = EPT_SPTE_MMU_WRITABLE;
 
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 0ed690f78e17..f5261d993eac 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -24,7 +24,7 @@
  * - bits 55 (EPT only): MMU-writable
  * - bits 56-59: unused
  * - bits 60-61: type of A/D tracking
- * - bits 62: unused
+ * - bits 62 (EPT only): saved XU bit for disabled AD
  */
 
 /*
@@ -65,7 +65,8 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
  * must not overlap the A/D type mask.
  */
 #define SHADOW_ACC_TRACK_SAVED_BITS_MASK (VMX_EPT_READABLE_MASK | \
-					  VMX_EPT_EXECUTABLE_MASK)
+					  VMX_EPT_EXECUTABLE_MASK | \
+					  VMX_EPT_USER_EXECUTABLE_MASK)
 #define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 52
 #define SHADOW_ACC_TRACK_SAVED_MASK	(SHADOW_ACC_TRACK_SAVED_BITS_MASK << \
 					 SHADOW_ACC_TRACK_SAVED_BITS_SHIFT)
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 7e59eb0f41bb..07469d1cfe74 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -15,6 +15,7 @@ extern bool __read_mostly enable_ept;
 extern bool __read_mostly enable_unrestricted_guest;
 extern bool __read_mostly enable_ept_ad_bits;
 extern bool __read_mostly enable_pml;
+extern bool __read_mostly enable_mbec;
 extern int __read_mostly pt_mode;
 
 #define PT_MODE_SYSTEM		0
@@ -406,4 +407,10 @@ static inline bool cpu_has_notify_vmexit(void)
 		SECONDARY_EXEC_NOTIFY_VM_EXITING;
 }
 
+static inline bool cpu_has_ept_mbec(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl &
+		SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
+}
+
 #endif /* __KVM_X86_VMX_CAPS_H */
diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index 1afbf272efae..40fa72f31fc7 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -91,15 +91,15 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
 	/* Is it a fetch fault? */
 	error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
 		      ? PFERR_FETCH_MASK : 0;
-	/*
-	 * ept page table entry is present?
-	 * note: unconditionally clear USER_EXEC until mode-based
-	 * execute control is implemented
-	 */
+	/* ept page table entry is present?  */
 	error_code |= (exit_qualification &
 		       (EPT_VIOLATION_PROT_MASK & ~EPT_VIOLATION_PROT_USER_EXEC))
 		      ? PFERR_PRESENT_MASK : 0;
 
+	if (mmu_has_mbec(vcpu->arch.mmu))
+		error_code |= (exit_qualification & EPT_VIOLATION_PROT_USER_EXEC)
+			      ? PFERR_PRESENT_MASK : 0;
+
 	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID)
 		error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) ?
 			      PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index dbebddf648be..83d9921277ea 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -755,6 +755,14 @@ static int vt_set_identity_map_addr(struct kvm *kvm, u64 ident_addr)
 	return vmx_set_identity_map_addr(kvm, ident_addr);
 }
 
+static bool vt_tdp_has_smep(struct kvm *kvm)
+{
+	if (is_td(kvm))
+		return false;
+
+	return vmx_tdp_has_smep(kvm);
+}
+
 static u64 vt_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
 {
 	/* TDX doesn't support L2 guest at the moment. */
@@ -966,6 +974,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.set_tss_addr = vt_op(set_tss_addr),
 	.set_identity_map_addr = vt_op(set_identity_map_addr),
 	.get_mt_mask = vmx_get_mt_mask,
+	.tdp_has_smep = vt_op(tdp_has_smep),
 
 	.get_exit_info = vt_op(get_exit_info),
 	.get_entry_info = vt_op(get_entry_info),
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index cd1924c6e075..299d4ca60fb3 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2440,6 +2440,7 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
 				  SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 				  SECONDARY_EXEC_APIC_REGISTER_VIRT |
 				  SECONDARY_EXEC_ENABLE_VMFUNC |
+				  SECONDARY_EXEC_MODE_BASED_EPT_EXEC |
 				  SECONDARY_EXEC_DESC);
 
 		if (nested_cpu_has(vmcs12,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 337bbfecc021..72a75fa33c93 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -114,6 +114,9 @@ module_param(emulate_invalid_guest_state, bool, 0444);
 static bool __read_mostly fasteoi = 1;
 module_param(fasteoi, bool, 0444);
 
+bool __read_mostly enable_mbec = 1;
+module_param_named(mbec, enable_mbec, bool, 0444);
+
 module_param(enable_apicv, bool, 0444);
 module_param(enable_ipiv, bool, 0444);
 
@@ -2773,6 +2776,7 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
 			return -EIO;
 
 		vmx_cap->ept = 0;
+		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
 		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_EPT_VIOLATION_VE;
 	}
 	if (!(_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_VPID) &&
@@ -4735,6 +4739,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	 */
 	exec_control &= ~SECONDARY_EXEC_ENABLE_VMFUNC;
 
+	if (!enable_mbec)
+		exec_control &= ~SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
+
 	/* SECONDARY_EXEC_DESC is enabled/disabled on writes to CR4.UMIP,
 	 * in vmx_set_cr4.  */
 	exec_control &= ~SECONDARY_EXEC_DESC;
@@ -7823,6 +7830,11 @@ u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 	return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT);
 }
 
+bool vmx_tdp_has_smep(struct kvm *kvm)
+{
+	return enable_mbec;
+}
+
 static void vmcs_set_secondary_exec_control(struct vcpu_vmx *vmx, u32 new_ctl)
 {
 	/*
@@ -8622,6 +8634,8 @@ __init int vmx_hardware_setup(void)
 
 	if (!cpu_has_vmx_ept_ad_bits() || !enable_ept)
 		enable_ept_ad_bits = 0;
+	if (!cpu_has_ept_mbec() || !enable_ept)
+		enable_mbec = 0;
 
 	if (!cpu_has_vmx_unrestricted_guest() || !enable_ept)
 		enable_unrestricted_guest = 0;
@@ -8683,7 +8697,7 @@ __init int vmx_hardware_setup(void)
 	set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
 
 	if (enable_ept)
-		kvm_mmu_set_ept_masks(enable_ept_ad_bits);
+		kvm_mmu_set_ept_masks(enable_ept_ad_bits, enable_mbec);
 	else
 		vt_x86_ops.get_mt_mask = NULL;
 
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index db84e8001da5..0a4e263c4095 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -567,6 +567,7 @@ static inline u8 vmx_get_rvi(void)
 	 SECONDARY_EXEC_ENABLE_VMFUNC |					\
 	 SECONDARY_EXEC_BUS_LOCK_DETECTION |				\
 	 SECONDARY_EXEC_NOTIFY_VM_EXITING |				\
+	 SECONDARY_EXEC_MODE_BASED_EPT_EXEC |				\
 	 SECONDARY_EXEC_ENCLS_EXITING |					\
 	 SECONDARY_EXEC_EPT_VIOLATION_VE)
 
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index d09abeac2b56..69cf276be88e 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -103,6 +103,7 @@ void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
 int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
 int vmx_set_identity_map_addr(struct kvm *kvm, u64 ident_addr);
 u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
+bool vmx_tdp_has_smep(struct kvm *kvm);
 
 void vmx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
 		       u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code);
-- 
2.52.0

Re: [PATCH 15/28] KVM: VMX: enable use of MBEC

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 337bbfecc021..72a75fa33c93 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -114,6 +114,9 @@ module_param(emulate_invalid_guest_state, bool, 0444);
>  static bool __read_mostly fasteoi = 1;
>  module_param(fasteoi, bool, 0444);
>  
> +bool __read_mostly enable_mbec = 1;
> +module_param_named(mbec, enable_mbec, bool, 0444);
> +

...

> @@ -7823,6 +7830,11 @@ u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
>  	return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT);
>  }
>  
> +bool vmx_tdp_has_smep(struct kvm *kvm)
> +{
> +	return enable_mbec;

Given that enable_mbec is made visible for nested.c anyways, I don't see any
reason to trampoline into vmx.c.  Ugh, never mind, because VMX needs to provide
a function for the ops hook when TDX support is disabled.

We could at least make vmx_tdp_has_smep() a static inline though.

> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index d09abeac2b56..69cf276be88e 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -103,6 +103,7 @@ void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
>  int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
>  int vmx_set_identity_map_addr(struct kvm *kvm, u64 ident_addr);
>  u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
> +bool vmx_tdp_has_smep(struct kvm *kvm);
>  
>  void vmx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
>  		       u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code);
> -- 
> 2.52.0
> 
> 

Re: [PATCH 15/28] KVM: VMX: enable use of MBEC

[David Riley]

see inline.

On 4/30/26 5:10 PM, Paolo Bonzini wrote:
> [...]
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 337bbfecc021..72a75fa33c93 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -114,6 +114,9 @@ module_param(emulate_invalid_guest_state, bool, 0444);
>   static bool __read_mostly fasteoi = 1;
>   module_param(fasteoi, bool, 0444);
>   
> +bool __read_mostly enable_mbec = 1;
> +module_param_named(mbec, enable_mbec, bool, 0444);
> +
>   module_param(enable_apicv, bool, 0444);
>   module_param(enable_ipiv, bool, 0444);
>   
> @@ -2773,6 +2776,7 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>   			return -EIO;
>   
>   		vmx_cap->ept = 0;
> +		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
>   		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_EPT_VIOLATION_VE;
>   	}
>   	if (!(_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_VPID) &&
> @@ -4735,6 +4739,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>   	 */
>   	exec_control &= ~SECONDARY_EXEC_ENABLE_VMFUNC;
>   
> +	if (!enable_mbec)
> +		exec_control &= ~SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
> +
>   	/* SECONDARY_EXEC_DESC is enabled/disabled on writes to CR4.UMIP,
>   	 * in vmx_set_cr4.  */
>   	exec_control &= ~SECONDARY_EXEC_DESC;
> @@ -7823,6 +7830,11 @@ u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
>   	return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT);
>   }
>   
> +bool vmx_tdp_has_smep(struct kvm *kvm)
> +{
> +	return enable_mbec;
> +}
> +
>   static void vmcs_set_secondary_exec_control(struct vcpu_vmx *vmx, u32 new_ctl)
>   {
>   	/*
> @@ -8622,6 +8634,8 @@ __init int vmx_hardware_setup(void)
>   
>   	if (!cpu_has_vmx_ept_ad_bits() || !enable_ept)
>   		enable_ept_ad_bits = 0;
> +	if (!cpu_has_ept_mbec() || !enable_ept)
> +		enable_mbec = 0;
>   
>   	if (!cpu_has_vmx_unrestricted_guest() || !enable_ept)
>   		enable_unrestricted_guest = 0;
> @@ -8683,7 +8697,7 @@ __init int vmx_hardware_setup(void)
>   	set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
>   
>   	if (enable_ept)
> -		kvm_mmu_set_ept_masks(enable_ept_ad_bits);
> +		kvm_mmu_set_ept_masks(enable_ept_ad_bits, enable_mbec);
This patch introduces a build failure for me on v7.1-rc2
(and v7.1-rc1) due to a function signature mismatch for
kvm_mmu_set_ept_masks.

In this patch, the call site in arch/x86/kvm/vmx/vmx.c is updated to
pass two arguments:
kvm_mmu_set_ept_masks(enable_ept_ad_bits, enable_mbec);

However, the definition in arch/x86/kvm/mmu/spte.c and the declaration
in arch/x86/kvm/mmu.h appear to have remained single-argument
functions:
void kvm_mmu_set_ept_masks(bool has_ad_bits);

This results in:
error: too many arguments to function ‘kvm_mmu_set_ept_masks’

>   	else
>   		vt_x86_ops.get_mt_mask = NULL;
>   
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index db84e8001da5..0a4e263c4095 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -567,6 +567,7 @@ static inline u8 vmx_get_rvi(void)
>   	 SECONDARY_EXEC_ENABLE_VMFUNC |					\
>   	 SECONDARY_EXEC_BUS_LOCK_DETECTION |				\
>   	 SECONDARY_EXEC_NOTIFY_VM_EXITING |				\
> +	 SECONDARY_EXEC_MODE_BASED_EPT_EXEC |				\
>   	 SECONDARY_EXEC_ENCLS_EXITING |					\
>   	 SECONDARY_EXEC_EPT_VIOLATION_VE)
>   
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index d09abeac2b56..69cf276be88e 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -103,6 +103,7 @@ void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
>   int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr);
>   int vmx_set_identity_map_addr(struct kvm *kvm, u64 ident_addr);
>   u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
> +bool vmx_tdp_has_smep(struct kvm *kvm);
>   
>   void vmx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
>   		       u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code);

[PATCH 16/28] KVM: nVMX: pass advanced EPT violation vmexit info to guest

[Paolo Bonzini]

KVM will use advanced vmexit information for EPT violations to
virtualize MBEC.  Pass it to the guest since it is easy and allows
testing nested nested.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/vmx.h     |  4 ++++
 arch/x86/kvm/mmu/paging_tmpl.h |  2 +-
 arch/x86/kvm/vmx/nested.c      | 13 +++++++++----
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 54aa5be50df9..ed2ded531e55 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -535,6 +535,7 @@ enum vmcs_field {
 #define VMX_EPT_1GB_PAGE_BIT			(1ull << 17)
 #define VMX_EPT_INVEPT_BIT			(1ull << 20)
 #define VMX_EPT_AD_BIT				    (1ull << 21)
+#define VMX_EPT_ADVANCED_VMEXIT_INFO_BIT	(1ull << 22)
 #define VMX_EPT_EXTENT_CONTEXT_BIT		(1ull << 25)
 #define VMX_EPT_EXTENT_GLOBAL_BIT		(1ull << 26)
 
@@ -617,6 +618,9 @@ enum vm_entry_failure_code {
 					 EPT_VIOLATION_PROT_USER_EXEC)
 #define EPT_VIOLATION_GVA_IS_VALID	BIT(7)
 #define EPT_VIOLATION_GVA_TRANSLATED	BIT(8)
+#define EPT_VIOLATION_GVA_USER		BIT(9)
+#define EPT_VIOLATION_GVA_WRITABLE	BIT(10)
+#define EPT_VIOLATION_GVA_NX		BIT(11)
 
 #define EPT_VIOLATION_RWX_TO_PROT(__epte) (((__epte) & VMX_EPT_RWX_MASK) << 3)
 #define EPT_VIOLATION_USER_EXEC_TO_PROT(__epte) (((__epte) & VMX_EPT_USER_EXECUTABLE_MASK) >> 4)
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 8dd9d510fc34..d4ce55195a7c 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -494,7 +494,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 	 * [2:0] - Derive from the access bits. The exit_qualification might be
 	 *         out of date if it is serving an EPT misconfiguration.
 	 * [5:3] - Calculated by the page walk of the guest EPT page tables
-	 * [7:8] - Derived from [7:8] of real exit_qualification
+	 * [7:11] - Derived from [7:11] of real exit_qualification
 	 *
 	 * The other bits are set to 0.
 	 */
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 299d4ca60fb3..46b65475765d 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -443,10 +443,14 @@ static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu,
 			vm_exit_reason = EXIT_REASON_EPT_MISCONFIG;
 			exit_qualification = 0;
 		} else {
+			u64 mask = EPT_VIOLATION_GVA_IS_VALID |
+				EPT_VIOLATION_GVA_TRANSLATED;
+			if (vmx->nested.msrs.ept_caps & VMX_EPT_ADVANCED_VMEXIT_INFO_BIT)
+				mask |= EPT_VIOLATION_GVA_USER |
+					       EPT_VIOLATION_GVA_WRITABLE |
+					       EPT_VIOLATION_GVA_NX;
 			exit_qualification = fault->exit_qualification;
-			exit_qualification |= vmx_get_exit_qual(vcpu) &
-					      (EPT_VIOLATION_GVA_IS_VALID |
-					       EPT_VIOLATION_GVA_TRANSLATED);
+			exit_qualification |= vmx_get_exit_qual(vcpu) & mask;
 			vm_exit_reason = EXIT_REASON_EPT_VIOLATION;
 		}
 
@@ -7240,7 +7244,8 @@ static void nested_vmx_setup_secondary_ctls(u32 ept_caps,
 			VMX_EPT_PAGE_WALK_5_BIT |
 			VMX_EPTP_WB_BIT |
 			VMX_EPT_INVEPT_BIT |
-			VMX_EPT_EXECUTE_ONLY_BIT;
+			VMX_EPT_EXECUTE_ONLY_BIT |
+			VMX_EPT_ADVANCED_VMEXIT_INFO_BIT;
 
 		msrs->ept_caps &= ept_caps;
 		msrs->ept_caps |= VMX_EPT_EXTENT_GLOBAL_BIT |
-- 
2.52.0

[PATCH 17/28] KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations

[Paolo Bonzini]

For EPT, PFERR_USER_MASK refers not to the CPL of the guest,
but to the AND of the U bits encountered while walking guest
page tables; this is consistent with how MBEC differentiates
between XS and XU.  This is available through the
"advanced vmexit information for EPT violations" feature.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/common.h |  6 +++++-
 arch/x86/kvm/vmx/vmx.c    | 10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
index 40fa72f31fc7..48520fa1c8e8 100644
--- a/arch/x86/kvm/vmx/common.h
+++ b/arch/x86/kvm/vmx/common.h
@@ -100,9 +100,13 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
 		error_code |= (exit_qualification & EPT_VIOLATION_PROT_USER_EXEC)
 			      ? PFERR_PRESENT_MASK : 0;
 
-	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID)
+	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID) {
 		error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) ?
 			      PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
+		if ((exit_qualification & (EPT_VIOLATION_GVA_TRANSLATED|EPT_VIOLATION_GVA_USER))
+		    == (EPT_VIOLATION_GVA_TRANSLATED|EPT_VIOLATION_GVA_USER))
+			error_code |= PFERR_USER_MASK;
+	}
 
 	if (vt_is_tdx_private_gpa(vcpu->kvm, gpa))
 		error_code |= PFERR_PRIVATE_ACCESS;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 72a75fa33c93..5e4aa519423c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2790,6 +2790,16 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
 		vmx_cap->vpid = 0;
 	}
 
+	/*
+	 * Virtualizing MBEC requires advanced vmexit information in order to
+	 * distinguish supervisor and user accesses.  For simplicity and clarity
+	 * disable MBEC entirely if advanced vmexit information is not available,
+	 * this way mbec=1 in the kvm_intel module parameters implies availability
+	 * to nested guests as well.
+	 */
+	if (!(vmx_cap->ept & VMX_EPT_ADVANCED_VMEXIT_INFO_BIT))
+		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
+
 	if (!cpu_has_sgx())
 		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_ENCLS_EXITING;
 
-- 
2.52.0

Re: [PATCH 17/28] KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> For EPT, PFERR_USER_MASK refers not to the CPL of the guest,
> but to the AND of the U bits encountered while walking guest
> page tables; this is consistent with how MBEC differentiates
> between XS and XU.  This is available through the
> "advanced vmexit information for EPT violations" feature.
> 
> Tested-by: David Riley <d.riley@proxmox.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/vmx/common.h |  6 +++++-
>  arch/x86/kvm/vmx/vmx.c    | 10 ++++++++++
>  2 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
> index 40fa72f31fc7..48520fa1c8e8 100644
> --- a/arch/x86/kvm/vmx/common.h
> +++ b/arch/x86/kvm/vmx/common.h
> @@ -100,9 +100,13 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
>  		error_code |= (exit_qualification & EPT_VIOLATION_PROT_USER_EXEC)
>  			      ? PFERR_PRESENT_MASK : 0;
>  
> -	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID)
> +	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID) {
>  		error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) ?
>  			      PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
> +		if ((exit_qualification & (EPT_VIOLATION_GVA_TRANSLATED|EPT_VIOLATION_GVA_USER))
> +		    == (EPT_VIOLATION_GVA_TRANSLATED|EPT_VIOLATION_GVA_USER))

Ow.  Maybe add a helper or a local const u64?  Actually, no need, just drop the
ternary operator above:

	if (exit_qualification & EPT_VIOLATION_GVA_IS_VALID) {
		if (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) {
			error_code |= PFERR_GUEST_FINAL_MASK;
			if (exit_qualification & EPT_VIOLATION_GVA_USER)
				error_code |= PFERR_USER_MASK;
		} else {
			error_code |= PFERR_GUEST_PAGE_MASK;
		}
	}

[PATCH 18/28] KVM: x86/mmu: add support for MBEC to EPT page table walks

[Paolo Bonzini]

Extend the page walker to support moving bit 10 of the PTEs
into ACC_USER_EXEC_MASK and bit 6 of the exit qualification of
EPT violation VM exits.

Note that while mmu_has_mbec()/cr4_smep affect the interpretation of
ACC_USER_EXEC_MASK and add bit 10 as a "present bit" in guest EPT page
table entries, they do not affect how KVM operates on SPTEs.  That's
because the MMU uses explicit ACC_USER_EXEC_MASK/shadow_xu_mask even for
the non-nested EPT; the only difference is that ACC_USER_EXEC_MASK and
ACC_EXEC_MASK will always be set in tandem outside the nested scenario.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/mmu.c         | 13 +++++++++++--
 arch/x86/kvm/mmu/paging_tmpl.h | 27 +++++++++++++++++++++------
 arch/x86/kvm/mmu/spte.h        |  2 ++
 arch/x86/kvm/vmx/nested.c      |  9 +++++++++
 4 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 245a2e92793d..fe87eee43b09 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5570,7 +5570,6 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 {
 	unsigned byte;
 
-	const u16 x = ACC_BITS_MASK(ACC_EXEC_MASK);
 	const u16 w = ACC_BITS_MASK(ACC_WRITE_MASK);
 	const u16 r = ACC_BITS_MASK(ACC_READ_MASK);
 
@@ -5611,8 +5610,18 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 		u16 smapf = 0;
 
 		if (ept) {
-			ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
+			const u16 xs = ACC_BITS_MASK(ACC_EXEC_MASK);
+			const u16 xu = ACC_BITS_MASK(ACC_USER_EXEC_MASK);
+
+			if (pfec & PFERR_FETCH_MASK) {
+				/* Ignore XU unless MBEC is enabled.  */
+				if (cr4_smep)
+					ff = pfec & PFERR_USER_MASK ? (u16)~xu : (u16)~xs;
+				else
+					ff = (u16)~xs;
+			}
 		} else {
+			const u16 x = ACC_BITS_MASK(ACC_EXEC_MASK);
 			const u16 u = ACC_BITS_MASK(ACC_USER_MASK);
 
 			/* Faults from kernel mode accesses to user pages */
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index d4ce55195a7c..f741f7d4cc2d 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -124,12 +124,17 @@ static inline void FNAME(protect_clean_gpte)(struct kvm_mmu *mmu, unsigned *acce
 	*access &= mask;
 }
 
-static inline int FNAME(is_present_gpte)(unsigned long pte)
+static inline int FNAME(is_present_gpte)(struct kvm_mmu *mmu,
+					 unsigned long pte)
 {
 #if PTTYPE != PTTYPE_EPT
 	return pte & PT_PRESENT_MASK;
 #else
-	return pte & 7;
+	/*
+	 * For EPT, an entry is present if any of bits 2:0 are set.
+	 * With mode-based execute control, bit 10 also indicates presence.
+	 */
+	return pte & (7 | (mmu_has_mbec(mmu) ? VMX_EPT_USER_EXECUTABLE_MASK : 0));
 #endif
 }
 
@@ -152,7 +157,7 @@ static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
 				  struct kvm_mmu_page *sp, u64 *spte,
 				  u64 gpte)
 {
-	if (!FNAME(is_present_gpte)(gpte))
+	if (!FNAME(is_present_gpte)(vcpu->arch.mmu, gpte))
 		goto no_present;
 
 	/* Prefetch only accessed entries (unless A/D bits are disabled). */
@@ -173,10 +178,17 @@ static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
 static inline unsigned FNAME(gpte_access)(u64 gpte)
 {
 	unsigned access;
+	/*
+	 * Set bits in ACC_*_MASK even if they might not be used in the
+	 * actual checks.  For example, if EFER.NX is clear permission_fault()
+	 * will ignore ACC_EXEC_MASK, and if MBEC is disabled it will
+	 * ignore ACC_USER_EXEC_MASK.
+	 */
 #if PTTYPE == PTTYPE_EPT
 	access = ((gpte & VMX_EPT_WRITABLE_MASK) ? ACC_WRITE_MASK : 0) |
 		((gpte & VMX_EPT_EXECUTABLE_MASK) ? ACC_EXEC_MASK : 0) |
-		((gpte & VMX_EPT_READABLE_MASK) ? ACC_READ_MASK : 0);
+		((gpte & VMX_EPT_READABLE_MASK) ? ACC_READ_MASK : 0) |
+		((gpte & VMX_EPT_USER_EXECUTABLE_MASK) ? ACC_USER_EXEC_MASK : 0);
 #else
 	/*
 	 * P is set here, so the page is always readable and W/U/!NX represent
@@ -331,7 +343,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 	if (walker->level == PT32E_ROOT_LEVEL) {
 		pte = mmu->get_pdptr(vcpu, (addr >> 30) & 3);
 		trace_kvm_mmu_paging_element(pte, walker->level);
-		if (!FNAME(is_present_gpte)(pte))
+		if (!FNAME(is_present_gpte)(mmu, pte))
 			goto error;
 		--walker->level;
 	}
@@ -414,7 +426,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 		 */
 		pte_access = pt_access & (pte ^ walk_nx_mask);
 
-		if (unlikely(!FNAME(is_present_gpte)(pte)))
+		if (unlikely(!FNAME(is_present_gpte)(mmu, pte)))
 			goto error;
 
 		if (unlikely(FNAME(is_rsvd_bits_set)(mmu, pte, walker->level))) {
@@ -521,6 +533,9 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 		 * ACC_*_MASK flags!
 		 */
 		walker->fault.exit_qualification |= EPT_VIOLATION_RWX_TO_PROT(pte_access);
+		if (mmu_has_mbec(mmu))
+			walker->fault.exit_qualification |=
+				EPT_VIOLATION_USER_EXEC_TO_PROT(pte_access);
 	}
 #endif
 	walker->fault.address = addr;
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index f5261d993eac..fe9571837fee 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -395,6 +395,8 @@ static inline bool __is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check,
 static inline bool __is_bad_mt_xwr(struct rsvd_bits_validate *rsvd_check,
 				   u64 pte)
 {
+	if (pte & VMX_EPT_USER_EXECUTABLE_MASK)
+		pte |= VMX_EPT_EXECUTABLE_MASK;
 	return rsvd_check->bad_mt_xwr & BIT_ULL(pte & 0x3f);
 }
 
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 46b65475765d..84f5c25a1f12 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7452,6 +7452,15 @@ static gpa_t vmx_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
 
 	BUG_ON(!mmu_is_nested(vcpu));
+
+	/*
+	 * MBEC differentiates based on the effective U/S bit of
+	 * the guest page tables; not the processor CPL.
+	 */
+	access &= ~PFERR_USER_MASK;
+	if ((pte_access & ACC_USER_MASK) && (access & PFERR_GUEST_FINAL_MASK))
+		access |= PFERR_USER_MASK;
+
 	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
 }
 
-- 
2.52.0

[PATCH 19/28] KVM: nVMX: advertise MBEC to nested guests

[Paolo Bonzini]

From: Jon Kohler <jon@nutanix.com>

Advertise SECONDARY_EXEC_MODE_BASED_EPT_EXEC (MBEC) to userspace, which
allows userspace to expose and advertise the feature to the guest.

When MBEC is enabled by the guest, it is passed to the MMU via cr4_smep,
and to the processor by the merging of vmcs12->secondary_vm_exec_control
into the VMCS02's secondary VM execution controls.

Signed-off-by: Jon Kohler <jon@nutanix.com>
Message-ID: <20251223054806.1611168-9-jon@nutanix.com>
Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu.h        |  2 +-
 arch/x86/kvm/mmu/mmu.c    |  7 ++++---
 arch/x86/kvm/mmu/spte.c   | 10 ++++++----
 arch/x86/kvm/vmx/nested.c | 11 +++++++++++
 4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 23bc5b18efd0..e1e3869f568b 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -100,7 +100,7 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
 			     unsigned long cr4, u64 efer, gpa_t nested_cr3);
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     int huge_page_level, bool accessed_dirty,
-			     gpa_t new_eptp);
+			     bool mbec, gpa_t new_eptp);
 bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu);
 int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
 				u64 fault_address, char *insn, int insn_len);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index fe87eee43b09..27776d0b2ad9 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5959,7 +5959,7 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_shadow_npt_mmu);
 
 static union kvm_cpu_role
 kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
-				   bool execonly, u8 level)
+				   bool execonly, u8 level, bool mbec)
 {
 	union kvm_cpu_role role = {0};
 
@@ -5969,6 +5969,7 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
 	 */
 	WARN_ON_ONCE(is_smm(vcpu));
 	role.base.level = level;
+	role.base.cr4_smep = mbec;
 	role.base.has_4_byte_gpte = false;
 	role.base.direct = false;
 	role.base.ad_disabled = !accessed_dirty;
@@ -5984,13 +5985,13 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
 
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     int huge_page_level, bool accessed_dirty,
-			     gpa_t new_eptp)
+			     bool mbec, gpa_t new_eptp)
 {
 	struct kvm_mmu *context = &vcpu->arch.guest_mmu;
 	u8 level = vmx_eptp_page_walk_level(new_eptp);
 	union kvm_cpu_role new_mode =
 		kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty,
-						   execonly, level);
+						   execonly, level, mbec);
 
 	if (new_mode.as_u64 != context->cpu_role.as_u64) {
 		/* EPT, and thus nested EPT, does not consume CR0, CR4, nor EFER. */
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 09e6f494dcf4..9b5ce4d1fa65 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -517,10 +517,12 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits)
 	 * host's MBEC setting does not matter.  On hardware without MBEC
 	 * the XU bit is reserved-as-ignored, and setting it does no harm.
 	 *
-	 * For nested EPT MBEC is not supported, but bit 10 of the gPTE has
-	 * no effect because (a) is_present_gpte() does not treat it as a
-	 * present bit, and (b) permission_fault() uses an mmu->permissions[]
-	 * array that effectively ignores ACC_USER_EXEC_MASK.
+	 * For nested EPT, when MBEC is disabled by L1, correctness relies
+	 * on (a) ignoring bit 10 of the gPTE in is_present_gpte(), rather
+	 * than treating it as a present bit, and (b) permission_fault()
+	 * using an mmu->permissions[] array that effectively ignores
+	 * ACC_USER_EXEC_MASK.  Bit 10 of the gPTE does end up mirrored
+	 * in the sPTEs but is ignored because L2 runs with MBEC disabled.
 	 */
 	shadow_xu_mask		= VMX_EPT_USER_EXECUTABLE_MASK;
 	shadow_present_mask	= VMX_EPT_SUPPRESS_VE_BIT;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 84f5c25a1f12..bc1046f32ebc 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -469,6 +469,13 @@ static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu,
 	vmcs12->guest_physical_address = fault->address;
 }
 
+static inline bool nested_ept_mbec_enabled(struct kvm_vcpu *vcpu)
+{
+	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+
+	return nested_cpu_has2(vmcs12, SECONDARY_EXEC_MODE_BASED_EPT_EXEC);
+}
+
 static void nested_ept_new_eptp(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -477,6 +484,7 @@ static void nested_ept_new_eptp(struct kvm_vcpu *vcpu)
 
 	kvm_init_shadow_ept_mmu(vcpu, execonly, ept_lpage_level,
 				nested_ept_ad_enabled(vcpu),
+				nested_ept_mbec_enabled(vcpu),
 				nested_ept_get_eptp(vcpu));
 }
 
@@ -7257,6 +7265,9 @@ static void nested_vmx_setup_secondary_ctls(u32 ept_caps,
 			msrs->ept_caps |= VMX_EPT_AD_BIT;
 		}
 
+		if (enable_mbec)
+			msrs->secondary_ctls_high |=
+				SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
 		/*
 		 * Advertise EPTP switching irrespective of hardware support,
 		 * KVM emulates it in software so long as VMFUNC is supported.
-- 
2.52.0

[PATCH 20/28] KVM: nVMX: allow MBEC with EVMCS

[Paolo Bonzini]

From: Jon Kohler <jon@nutanix.com>

Extend EVMCS1_SUPPORTED_2NDEXEC to allow MBEC and EVMCS to coexist.
Presenting both EVMCS and MBEC simultaneously causes KVM to filter out
MBEC and not present it as a supported control to the guest, preventing
performance gains from MBEC when Windows HVCI is enabled.

The guest may choose not to use MBEC (e.g., if the admin does not enable
Windows HVCI / Memory Integrity), but if they use traditional nested
virt (Hyper-V, WSL2, etc.), having EVMCS exposed is important for
improving nested guest performance. IOW allowing MBEC and EVMCS to
coexist provides maximum optionality to Windows users without
overcomplicating VM administration.

Signed-off-by: Jon Kohler <jon@nutanix.com>
Message-ID: <20251223054806.1611168-8-jon@nutanix.com>
Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/hyperv_evmcs.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/vmx/hyperv_evmcs.h b/arch/x86/kvm/vmx/hyperv_evmcs.h
index fc7c4e7bd1bf..bc08fe40590e 100644
--- a/arch/x86/kvm/vmx/hyperv_evmcs.h
+++ b/arch/x86/kvm/vmx/hyperv_evmcs.h
@@ -87,6 +87,7 @@
 	 SECONDARY_EXEC_PT_CONCEAL_VMX |				\
 	 SECONDARY_EXEC_BUS_LOCK_DETECTION |				\
 	 SECONDARY_EXEC_NOTIFY_VM_EXITING |				\
+	 SECONDARY_EXEC_MODE_BASED_EPT_EXEC |				\
 	 SECONDARY_EXEC_ENCLS_EXITING)
 
 #define EVMCS1_SUPPORTED_3RDEXEC (0ULL)
-- 
2.52.0

[PATCH 21/28] KVM: x86/mmu: propagate access mask from root pages down

[Paolo Bonzini]

Until now, all SPTEs have had all kinds of access allowed; however,
for GMET to be enabled all the pages have to have ACC_USER_MASK
disabled.  By marking them as supervisor pages, the processor
allows execution from either user or supervisor mode (unlike
for normal paging, NPT ignores the U bit for reads and writes).
That will mean that the root page's role has ACC_USER_MASK
cleared and that has to be propagated down through the kvm_mmu_page
tree.

Do that, and pass the required access to the
kvm_mmu_spte_requested tracepoint since it's not ACC_ALL
anymore.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/mmu.c         |  9 +++++----
 arch/x86/kvm/mmu/mmutrace.h    | 10 ++++++----
 arch/x86/kvm/mmu/paging_tmpl.h |  2 +-
 arch/x86/kvm/mmu/tdp_mmu.c     |  6 +++---
 4 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 27776d0b2ad9..5836ff595e32 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3446,12 +3446,13 @@ static int direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 {
 	struct kvm_shadow_walk_iterator it;
 	struct kvm_mmu_page *sp;
-	int ret;
+	int ret, access;
 	gfn_t base_gfn = fault->gfn;
 
 	kvm_mmu_hugepage_adjust(vcpu, fault);
 
-	trace_kvm_mmu_spte_requested(fault);
+	access = vcpu->arch.mmu->root_role.access;
+	trace_kvm_mmu_spte_requested(fault, access);
 	for_each_shadow_entry(vcpu, fault->addr, it) {
 		/*
 		 * We cannot overwrite existing page tables with an NX
@@ -3464,7 +3465,7 @@ static int direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 		if (it.level == fault->goal_level)
 			break;
 
-		sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL);
+		sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, access);
 		if (sp == ERR_PTR(-EEXIST))
 			continue;
 
@@ -3477,7 +3478,7 @@ static int direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	if (WARN_ON_ONCE(it.level != fault->goal_level))
 		return -EFAULT;
 
-	ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL,
+	ret = mmu_set_spte(vcpu, fault->slot, it.sptep, access,
 			   base_gfn, fault->pfn, fault);
 	if (ret == RET_PF_SPURIOUS)
 		return ret;
diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h
index 3429c1413f42..fa01719baf8d 100644
--- a/arch/x86/kvm/mmu/mmutrace.h
+++ b/arch/x86/kvm/mmu/mmutrace.h
@@ -373,23 +373,25 @@ TRACE_EVENT(
 
 TRACE_EVENT(
 	kvm_mmu_spte_requested,
-	TP_PROTO(struct kvm_page_fault *fault),
-	TP_ARGS(fault),
+	TP_PROTO(struct kvm_page_fault *fault, u8 access),
+	TP_ARGS(fault, access),
 
 	TP_STRUCT__entry(
 		__field(u64, gfn)
 		__field(u64, pfn)
 		__field(u8, level)
+		__field(u8, access)
 	),
 
 	TP_fast_assign(
 		__entry->gfn = fault->gfn;
 		__entry->pfn = fault->pfn | (fault->gfn & (KVM_PAGES_PER_HPAGE(fault->goal_level) - 1));
 		__entry->level = fault->goal_level;
+		__entry->access = access;
 	),
 
-	TP_printk("gfn %llx pfn %llx level %d",
-		  __entry->gfn, __entry->pfn, __entry->level
+	TP_printk("gfn %llx pfn %llx level %d access %x",
+		  __entry->gfn, __entry->pfn, __entry->level, __entry->access
 	)
 );
 
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index f741f7d4cc2d..047400af924d 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -734,7 +734,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
 	 */
 	kvm_mmu_hugepage_adjust(vcpu, fault);
 
-	trace_kvm_mmu_spte_requested(fault);
+	trace_kvm_mmu_spte_requested(fault, gw->pte_access);
 
 	for (; shadow_walk_okay(&it); shadow_walk_next(&it)) {
 		/*
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 7b1102d26f9c..5a2f8ce9a32b 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1185,9 +1185,9 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
 	}
 
 	if (unlikely(!fault->slot))
-		new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL);
+		new_spte = make_mmio_spte(vcpu, iter->gfn, sp->role.access);
 	else
-		wrprot = make_spte(vcpu, sp, fault->slot, ACC_ALL, iter->gfn,
+		wrprot = make_spte(vcpu, sp, fault->slot, sp->role.access, iter->gfn,
 				   fault->pfn, iter->old_spte, fault->prefetch,
 				   false, fault->map_writable, &new_spte);
 
@@ -1272,7 +1272,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 
 	kvm_mmu_hugepage_adjust(vcpu, fault);
 
-	trace_kvm_mmu_spte_requested(fault);
+	trace_kvm_mmu_spte_requested(fault, root->role.access);
 
 	rcu_read_lock();
 
-- 
2.52.0

[PATCH 22/28] KVM: x86/mmu: introduce cpu_role bit for availability of PFEC.I/D

[Paolo Bonzini]

While GMET looks a lot like SMEP, it has several annoying differences.
The main one is that the availability of the I/D bit in the page fault
error code still depends on the host CR4.SMEP and EFER.NXE bits.  If the
base.cr4_smep bit of the cpu_role is (ab)used to enable GMET, there needs
to be another place where the host CR4.SMEP is read from; just merge it
with EFER.NXE into a new cpu_role bit that tells paging_tmpl.h whether
to set the I/D bit at all.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/kvm_host.h | 7 +++++++
 arch/x86/kvm/mmu/mmu.c          | 8 ++++++++
 arch/x86/kvm/mmu/paging_tmpl.h  | 2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 23a7ac8d7fbe..7dde4ca87752 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -414,6 +414,13 @@ union kvm_mmu_extended_role {
 		unsigned int cr4_smap:1;
 		unsigned int cr4_la57:1;
 		unsigned int efer_lma:1;
+
+		/*
+		 * True if either CR4.SMEP or EFER.NXE are set.  For AMD NPT
+		 * this is the "real" host CR4.SMEP whereas cr4_smep is
+		 * actually GMET.
+		 */
+		unsigned int has_pferr_fetch:1;
 	};
 };
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 5836ff595e32..93f96673d02a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -234,6 +234,11 @@ BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, la57);
 BUILD_MMU_ROLE_ACCESSOR(base, efer, nx);
 BUILD_MMU_ROLE_ACCESSOR(ext,  efer, lma);
 
+static inline bool has_pferr_fetch(struct kvm_mmu *mmu)
+{
+	return mmu->cpu_role.ext.has_pferr_fetch;
+}
+
 static inline bool is_cr0_pg(struct kvm_mmu *mmu)
 {
         return mmu->cpu_role.base.level > 0;
@@ -5793,6 +5798,8 @@ static union kvm_cpu_role kvm_calc_cpu_role(struct kvm_vcpu *vcpu,
 	role.ext.cr4_pke = ____is_efer_lma(regs) && ____is_cr4_pke(regs);
 	role.ext.cr4_la57 = ____is_efer_lma(regs) && ____is_cr4_la57(regs);
 	role.ext.efer_lma = ____is_efer_lma(regs);
+
+	role.ext.has_pferr_fetch = role.base.efer_nx | role.base.cr4_smep;
 	return role;
 }
 
@@ -5946,6 +5953,7 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
 
 	/* NPT requires CR0.PG=1. */
 	WARN_ON_ONCE(cpu_role.base.direct || !cpu_role.base.guest_mode);
+	cpu_role.base.cr4_smep = false;
 
 	root_role = cpu_role.base;
 	root_role.level = kvm_mmu_get_tdp_level(vcpu);
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 047400af924d..07100bbfc270 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -489,7 +489,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 
 error:
 	errcode |= write_fault | user_fault;
-	if (fetch_fault && (is_efer_nx(mmu) || is_cr4_smep(mmu)))
+	if (fetch_fault && has_pferr_fetch(mmu))
 		errcode |= PFERR_FETCH_MASK;
 
 	walker->fault.vector = PF_VECTOR;
-- 
2.52.0

[PATCH 23/28] KVM: SVM: add GMET bit definitions

[Paolo Bonzini]

GMET (Guest Mode Execute Trap) is an AMD virtualization feature,
essentially the nested paging version of SMEP.  Hyper-V uses it;
add it in preparation for making it available to hypervisors
running under KVM.

Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/include/asm/svm.h         | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index de7bd88e539d..d58dbce83f45 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -379,6 +379,7 @@
 #define X86_FEATURE_AVIC		(15*32+13) /* "avic" Virtual Interrupt Controller */
 #define X86_FEATURE_V_VMSAVE_VMLOAD	(15*32+15) /* "v_vmsave_vmload" Virtual VMSAVE VMLOAD */
 #define X86_FEATURE_VGIF		(15*32+16) /* "vgif" Virtual GIF */
+#define X86_FEATURE_GMET		(15*32+17) /* Guest Mode Execution Trap */
 #define X86_FEATURE_X2AVIC		(15*32+18) /* "x2avic" Virtual x2apic */
 #define X86_FEATURE_V_SPEC_CTRL		(15*32+20) /* "v_spec_ctrl" Virtual SPEC_CTRL */
 #define X86_FEATURE_VNMI		(15*32+25) /* "vnmi" Virtual NMI */
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index bcfeb5e7c0ed..aa63431ba92c 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -243,6 +243,7 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define SVM_MISC_ENABLE_NP		BIT(0)
 #define SVM_MISC_ENABLE_SEV		BIT(1)
 #define SVM_MISC_ENABLE_SEV_ES	BIT(2)
+#define SVM_MISC_ENABLE_GMET	BIT(3)
 
 #define SVM_MISC2_ENABLE_V_LBR	BIT_ULL(0)
 #define SVM_MISC2_ENABLE_V_VMLOAD_VMSAVE	BIT_ULL(1)
-- 
2.52.0

[PATCH 24/28] KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu

[Paolo Bonzini]

The host CR0 does not really reflect onto the NPT format because
hCR0.PG=1 must be set and hCR0.WP is ignored.  Carve that in stone
by removing the cr0 argument from kvm_init_shadow_npt_mmu.

Pass in WP=1 as well; it does not matter for GMET disabled because
PFERR_USER_MASK is always set, but a cleared W bit in the nested page
tables cannot be overridden in supervisor mode when GMET is enabled,
either.  In fact, since CR0.WP=0 is the weird "extra accesses allowed"
mode, it is acutally easier think about it being always set.

Likewise, clear X86_CR4_SMAP to avoid that KVM erroneously faults on
supervisor accesses to an U=1 page.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu.h        | 4 ++--
 arch/x86/kvm/mmu/mmu.c    | 8 ++++----
 arch/x86/kvm/svm/nested.c | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index e1e3869f568b..1b354e1f2d81 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -96,8 +96,8 @@ void kvm_mmu_set_me_spte_mask(u64 me_value, u64 me_mask);
 void kvm_mmu_set_ept_masks(bool has_ad_bits);
 
 void kvm_init_mmu(struct kvm_vcpu *vcpu);
-void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
-			     unsigned long cr4, u64 efer, gpa_t nested_cr3);
+void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
+			     u64 efer, gpa_t nested_cr3);
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     int huge_page_level, bool accessed_dirty,
 			     bool mbec, gpa_t new_eptp);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 93f96673d02a..32845edd14fa 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5939,13 +5939,13 @@ static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
 	shadow_mmu_init_context(vcpu, context, cpu_role, root_role);
 }
 
-void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
-			     unsigned long cr4, u64 efer, gpa_t nested_cr3)
+void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
+			     u64 efer, gpa_t nested_cr3)
 {
 	struct kvm_mmu *context = &vcpu->arch.guest_mmu;
 	struct kvm_mmu_role_regs regs = {
-		.cr0 = cr0,
-		.cr4 = cr4 & ~X86_CR4_PKE,
+		.cr0 = X86_CR0_PG | X86_CR0_WP,
+		.cr4 = cr4 & ~(X86_CR4_PKE | X86_CR4_SMAP),
 		.efer = efer,
 	};
 	union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, &regs);
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index df232153eb24..a1cffd274000 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -93,7 +93,7 @@ static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
 	 * when called via KVM_SET_NESTED_STATE, that state may _not_ match current
 	 * vCPU state.  CR0.WP is explicitly ignored, while CR0.PG is required.
 	 */
-	kvm_init_shadow_npt_mmu(vcpu, X86_CR0_PG, svm->vmcb01.ptr->save.cr4,
+	kvm_init_shadow_npt_mmu(vcpu, svm->vmcb01.ptr->save.cr4,
 				svm->vmcb01.ptr->save.efer,
 				svm->nested.ctl.nested_cr3);
 	vcpu->arch.mmu->get_guest_pgd     = nested_svm_get_tdp_cr3;
-- 
2.52.0

Re: [PATCH 24/28] KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> Likewise, clear X86_CR4_SMAP to avoid that KVM erroneously faults on
> supervisor accesses to an U=1 page.

What, don't you want to more closely follow real hardware?  :-D

Re: [PATCH 24/28] KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu

[Paolo Bonzini]

On Thu, Apr 30, 2026 at 9:09 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> > Likewise, clear X86_CR4_SMAP to avoid that KVM erroneously faults on
> > supervisor accesses to an U=1 page.
>
> What, don't you want to more closely follow real hardware?  :-D

Uh, I cannot parse this. Is there an errata I don't know about?

Paolo

Re: [PATCH 24/28] KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu

[Sean Christopherson]

On Fri, May 01, 2026, Paolo Bonzini wrote:
> On Thu, Apr 30, 2026 at 9:09 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> > > Likewise, clear X86_CR4_SMAP to avoid that KVM erroneously faults on
> > > supervisor accesses to an U=1 page.
> >
> > What, don't you want to more closely follow real hardware?  :-D
> 
> Uh, I cannot parse this. Is there an errata I don't know about?

Errata 1096, where the decode assist fails because the CPU tries to read the code
stream with data reads and trips SMAP.  Not a truly spurious fault since it's not
software visible, but I couldn't resist the joke :-)

[PATCH 25/28] KVM: x86/mmu: add support for GMET to NPT page table walks

[Paolo Bonzini]

GMET allows page table entries to be created with U=0 in NPT.
However, when GMET=1 U=0 only affects execution, not reads or
writes.  Ignore user faults on non-fetch accesses for NPT GMET.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  2 ++
 arch/x86/kvm/mmu.h              |  2 +-
 arch/x86/kvm/mmu/mmu.c          | 18 ++++++++++++------
 arch/x86/kvm/svm/nested.c       | 10 +++++++---
 4 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7dde4ca87752..1da3d5c59e15 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -370,6 +370,8 @@ union kvm_mmu_page_role {
 		 * cr4_smep is also set for EPT MBEC.  Because it affects
 		 * which pages are considered non-present (bit 10 additionally
 		 * must be zero if MBEC is on) it has to be in the base role.
+		 * It also has to be in the base role for AMD GMET because
+		 * kernel-executable pages need to have U=0 with GMET enabled.
 		 */
 		unsigned cr4_smep:1;
 
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 1b354e1f2d81..ddf4e467c071 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -97,7 +97,7 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits);
 
 void kvm_init_mmu(struct kvm_vcpu *vcpu);
 void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
-			     u64 efer, gpa_t nested_cr3);
+			     u64 efer, gpa_t nested_cr3, u64 misc_ctl);
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     int huge_page_level, bool accessed_dirty,
 			     bool mbec, gpa_t new_eptp);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 32845edd14fa..015085ef6e46 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -55,6 +55,7 @@
 #include <asm/io.h>
 #include <asm/set_memory.h>
 #include <asm/spec-ctrl.h>
+#include <asm/svm.h>
 #include <asm/vmx.h>
 
 #include "trace.h"
@@ -5572,7 +5573,7 @@ reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly)
 	 (14 & (access) ? 1 << 14 : 0) | \
 	 (15 & (access) ? 1 << 15 : 0))
 
-static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
+static void update_permission_bitmask(struct kvm_mmu *mmu, bool tdp, bool ept)
 {
 	unsigned byte;
 
@@ -5633,7 +5634,12 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
 			/* Faults from kernel mode accesses to user pages */
 			u16 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
 
-			uf = (pfec & PFERR_USER_MASK) ? (u16)~u : 0;
+			/*
+			 * For NPT GMET, U=0 does not affect reads and writes.  Fetches
+			 * are handled below via cr4_smep.
+			 */
+			if (!(tdp && cr4_smep))
+				uf = (pfec & PFERR_USER_MASK) ? (u16)~u : 0;
 
 			if (efer_nx)
 				ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
@@ -5744,7 +5750,7 @@ static void reset_guest_paging_metadata(struct kvm_vcpu *vcpu,
 		return;
 
 	reset_guest_rsvds_bits_mask(vcpu, mmu);
-	update_permission_bitmask(mmu, false);
+	update_permission_bitmask(mmu, mmu == &vcpu->arch.guest_mmu, false);
 	update_pkru_bitmask(mmu);
 }
 
@@ -5940,7 +5946,7 @@ static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
 }
 
 void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
-			     u64 efer, gpa_t nested_cr3)
+			     u64 efer, gpa_t nested_cr3, u64 misc_ctl)
 {
 	struct kvm_mmu *context = &vcpu->arch.guest_mmu;
 	struct kvm_mmu_role_regs regs = {
@@ -5953,7 +5959,7 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
 
 	/* NPT requires CR0.PG=1. */
 	WARN_ON_ONCE(cpu_role.base.direct || !cpu_role.base.guest_mode);
-	cpu_role.base.cr4_smep = false;
+	cpu_role.base.cr4_smep = (misc_ctl & SVM_MISC_ENABLE_GMET) != 0;
 
 	root_role = cpu_role.base;
 	root_role.level = kvm_mmu_get_tdp_level(vcpu);
@@ -6011,7 +6017,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 		context->gva_to_gpa = ept_gva_to_gpa;
 		context->sync_spte = ept_sync_spte;
 
-		update_permission_bitmask(context, true);
+		update_permission_bitmask(context, true, true);
 		context->pkru_mask = 0;
 		reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level);
 		reset_ept_shadow_zero_bits_mask(context, execonly);
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index a1cffd274000..7adfa7da210d 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -95,7 +95,8 @@ static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
 	 */
 	kvm_init_shadow_npt_mmu(vcpu, svm->vmcb01.ptr->save.cr4,
 				svm->vmcb01.ptr->save.efer,
-				svm->nested.ctl.nested_cr3);
+				svm->nested.ctl.nested_cr3,
+				svm->nested.ctl.misc_ctl);
 	vcpu->arch.mmu->get_guest_pgd     = nested_svm_get_tdp_cr3;
 	vcpu->arch.mmu->get_pdptr         = nested_svm_get_tdp_pdptr;
 	vcpu->arch.mmu->inject_page_fault = nested_svm_inject_npf_exit;
@@ -2076,12 +2077,15 @@ static gpa_t svm_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
 				      struct x86_exception *exception,
 				      u64 pte_access)
 {
+	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
 
 	BUG_ON(!mmu_is_nested(vcpu));
 
-	/* NPT walks are always user-walks */
-	access |= PFERR_USER_MASK;
+	/* Non-GMET walks are always user-walks */
+	if (!(svm->nested.ctl.misc_ctl & SVM_MISC_ENABLE_GMET))
+		access |= PFERR_USER_MASK;
+
 	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
 }
 
-- 
2.52.0

[PATCH 26/28] KVM: SVM: enable GMET and set it in MMU role

[Paolo Bonzini]

Set the GMET bit in the nested control field.  This has effectively
no impact as long as NPT page tables are changed to have U=0.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu/mmu.c    |  6 +++++-
 arch/x86/kvm/svm/nested.c |  9 ++++++---
 arch/x86/kvm/svm/svm.c    | 16 ++++++++++++++++
 arch/x86/kvm/svm/svm.h    |  1 +
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 015085ef6e46..31c1803d9d15 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5855,7 +5855,6 @@ kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu,
 {
 	union kvm_mmu_page_role role = {0};
 
-	role.access = ACC_ALL;
 	role.cr0_wp = true;
 	role.cr4_smep = kvm_x86_call(tdp_has_smep)(vcpu->kvm);
 	role.efer_nx = true;
@@ -5866,6 +5865,11 @@ kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu,
 	role.direct = true;
 	role.has_4_byte_gpte = false;
 
+	/* All TDP pages are supervisor-executable */
+	role.access = ACC_ALL;
+	if (role.cr4_smep && shadow_user_mask)
+		role.access &= ~ACC_USER_MASK;
+
 	return role;
 }
 
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 7adfa7da210d..74a1df1cb84f 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -858,7 +858,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	 * the latter, L1 runs L2 with shadow page tables that translate L2 GVAs
 	 * to L1 GPAs, so the same NPTs can be used for L1 and L2.
 	 */
-	vmcb02->control.misc_ctl = vmcb01->control.misc_ctl & SVM_MISC_ENABLE_NP;
+	vmcb02->control.misc_ctl = vmcb01->control.misc_ctl & (SVM_MISC_ENABLE_NP | SVM_MISC_ENABLE_GMET);
 	vmcb02->control.iopm_base_pa = vmcb01->control.iopm_base_pa;
 	vmcb02->control.msrpm_base_pa = vmcb01->control.msrpm_base_pa;
 	vmcb_mark_dirty(vmcb02, VMCB_PERM_MAP);
@@ -895,9 +895,12 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	/* Also overwritten later if necessary.  */
 	vmcb02->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
 
-	/* nested_cr3.  */
-	if (nested_npt_enabled(svm))
+	/* Use vmcb01 MMU and format if guest does not use nNPT */
+	if (nested_npt_enabled(svm)) {
+		vmcb02->control.misc_ctl &= ~SVM_MISC_ENABLE_GMET;
+
 		nested_svm_init_mmu_context(vcpu);
+	}
 
 	vcpu->arch.tsc_offset = kvm_calc_nested_tsc_offset(vcpu->arch.l1_tsc_offset,
 							   vmcb12_ctrl->tsc_offset,
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e7fdd7a9c280..3895d8794366 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -138,6 +138,9 @@ module_param(pause_filter_count_max, ushort, 0444);
 bool __ro_after_init npt_enabled = true;
 module_param_named(npt, npt_enabled, bool, 0444);
 
+bool gmet_enabled = true;
+module_param_named(gmet, gmet_enabled, bool, 0444);
+
 /* allow nested virtualization in KVM/SVM */
 static int __ro_after_init nested = true;
 module_param(nested, int, 0444);
@@ -1209,6 +1212,10 @@ static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event)
 		save->g_pat = vcpu->arch.pat;
 		save->cr3 = 0;
 	}
+
+	if (gmet_enabled)
+		control->misc_ctl |= SVM_MISC_ENABLE_GMET;
+
 	svm->current_vmcb->asid_generation = 0;
 	svm->asid = 0;
 
@@ -4612,6 +4619,11 @@ svm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
 	hypercall[2] = 0xd9;
 }
 
+static bool svm_tdp_has_smep(struct kvm *kvm)
+{
+	return gmet_enabled;
+}
+
 /*
  * The kvm parameter can be NULL (module initialization, or invocation before
  * VM creation). Be sure to check the kvm parameter before using it.
@@ -5355,6 +5367,7 @@ struct kvm_x86_ops svm_x86_ops __initdata = {
 	.write_tsc_multiplier = svm_write_tsc_multiplier,
 
 	.load_mmu_pgd = svm_load_mmu_pgd,
+	.tdp_has_smep = svm_tdp_has_smep,
 
 	.check_intercept = svm_check_intercept,
 	.handle_exit_irqoff = svm_handle_exit_irqoff,
@@ -5588,6 +5601,9 @@ static __init int svm_hardware_setup(void)
 	if (!boot_cpu_has(X86_FEATURE_NPT))
 		npt_enabled = false;
 
+	if (!npt_enabled || !boot_cpu_has(X86_FEATURE_GMET))
+		gmet_enabled = false;
+
 	/* Force VM NPT level equal to the host's paging level */
 	kvm_configure_mmu(npt_enabled, get_npt_level(),
 			  get_npt_level(), PG_LEVEL_1G);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index a10668d17a16..dd93b3daefa9 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -44,6 +44,7 @@ static inline struct page *__sme_pa_to_page(unsigned long pa)
 #define	IOPM_SIZE PAGE_SIZE * 3
 #define	MSRPM_SIZE PAGE_SIZE * 2
 
+extern bool gmet_enabled;
 extern bool npt_enabled;
 extern int nrips;
 extern int vgif;
-- 
2.52.0

Re: [PATCH 26/28] KVM: SVM: enable GMET and set it in MMU role

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index e7fdd7a9c280..3895d8794366 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -138,6 +138,9 @@ module_param(pause_filter_count_max, ushort, 0444);
>  bool __ro_after_init npt_enabled = true;
>  module_param_named(npt, npt_enabled, bool, 0444);
>  
> +bool gmet_enabled = true;

This really should be hardcoded false, with no module param, until "enable GMET
for guests".  Otherwise stopping here means KVM is over-reporting support.

I think the same goes for MBEC.  IIUC, KVM doesn't fully support MBEC until
"KVM: nVMX: advertise MBEC to nested guests".

Re: [PATCH 26/28] KVM: SVM: enable GMET and set it in MMU role

[Paolo Bonzini]

On Thu, Apr 30, 2026 at 9:15 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index e7fdd7a9c280..3895d8794366 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -138,6 +138,9 @@ module_param(pause_filter_count_max, ushort, 0444);
> >  bool __ro_after_init npt_enabled = true;
> >  module_param_named(npt, npt_enabled, bool, 0444);
> >
> > +bool gmet_enabled = true;
>
> This really should be hardcoded false, with no module param, until "enable GMET
> for guests".  Otherwise stopping here means KVM is over-reporting support.

Are module parameters reporting support of nested features? I thought
of these as "does KVM know about MBEC/GMET".

This is I think the only point where I disagree, I think. I'll fix up
patches 6/7/8/17.

Paolo

Re: [PATCH 26/28] KVM: SVM: enable GMET and set it in MMU role

[Sean Christopherson]

On Fri, May 01, 2026, Paolo Bonzini wrote:
> On Thu, Apr 30, 2026 at 9:15 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > > index e7fdd7a9c280..3895d8794366 100644
> > > --- a/arch/x86/kvm/svm/svm.c
> > > +++ b/arch/x86/kvm/svm/svm.c
> > > @@ -138,6 +138,9 @@ module_param(pause_filter_count_max, ushort, 0444);
> > >  bool __ro_after_init npt_enabled = true;
> > >  module_param_named(npt, npt_enabled, bool, 0444);
> > >
> > > +bool gmet_enabled = true;
> >
> > This really should be hardcoded false, with no module param, until "enable GMET
> > for guests".  Otherwise stopping here means KVM is over-reporting support.
> 
> Are module parameters reporting support of nested features?

Not strictly speaking, no.  But I do think most users, myself included, assume
that feature xyz is fully supported if its associated module param exist.  Though
I completely agree this is an unusual case since the MBEC/GMET aren't really
supported for non-nested, but KVM still consumes the module param.

> This is I think the only point where I disagree, I think.

No worries, I'm a-ok with this one as-is.  And I can see it being useful as a
bisection point.

[PATCH 27/28] KVM: SVM: work around errata 1218

[Paolo Bonzini]

According to AMD, the hypervisor may not be able to determine whether a
fault was a GMET fault or an NX fault based on EXITINFO1, and software
"must read the relevant VMCB to determine whether a fault was a GMET
fault or an NX fault".  The APM further details that they meant the
CPL field.

KVM uses the page fault error code to distinguish the causes of a
nested page fault, so recalculate the PFERR_USER_MASK bit of the
vmexit information.  Only do it for fetches and only if GMET is in
use, because KVM does not differentiate based on PFERR_USER_MASK
for other nested NPT page faults.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/svm/svm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 3895d8794366..fd79874c5f4b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1993,6 +1993,18 @@ static int npf_interception(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (!is_sev_es_guest(vcpu) &&
+	    (svm->vmcb->control.misc_ctl & SVM_MISC_ENABLE_GMET) &&
+	    (error_code & PFERR_FETCH_MASK)) {
+		/*
+		 * Work around errata 1218: EXITINFO1[2] May Be Incorrectly Set
+		 * When GMET (Guest Mode Execute Trap extension) is Enabled
+		 */
+		error_code |= PFERR_USER_MASK;
+		if (svm_get_cpl(vcpu) != 3)
+			error_code &= ~PFERR_USER_MASK;
+	}
+
 	if (is_sev_snp_guest(vcpu) && (error_code & PFERR_GUEST_ENC_MASK))
 		error_code |= PFERR_PRIVATE_ACCESS;
 
-- 
2.52.0

[PATCH 28/28] KVM: nSVM: enable GMET for guests

[Paolo Bonzini]

All that needs to be done is moving the GMET bit from vmcb12 to vmcb02.
The only new thing is that __nested_copy_vmcb_control_to_cache now
ensures that ignored-if-unavailable bits are zero in svm->nested.ctl.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/svm/nested.c | 6 +++++-
 arch/x86/kvm/svm/svm.c    | 3 +++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 74a1df1cb84f..3d1fd1776e19 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -489,11 +489,14 @@ void __nested_copy_vmcb_control_to_cache(struct kvm_vcpu *vcpu,
 	nested_svm_sanitize_intercept(vcpu, to, SKINIT);
 	nested_svm_sanitize_intercept(vcpu, to, RDPRU);
 
-	/* Always clear SVM_MISC_ENABLE_NP if the guest cannot use NPTs */
+	/* Always clear misc_ctl bits that the guest cannot use */
 	to->misc_ctl = from->misc_ctl;
 	if (!guest_cpu_cap_has(vcpu, X86_FEATURE_NPT))
 		to->misc_ctl &= ~SVM_MISC_ENABLE_NP;
 
+	if (!gmet_enabled || !guest_cpu_cap_has(vcpu, X86_FEATURE_GMET))
+		to->misc_ctl &= ~SVM_MISC_ENABLE_GMET;
+
 	to->iopm_base_pa        = from->iopm_base_pa & PAGE_MASK;
 	to->msrpm_base_pa       = from->msrpm_base_pa & PAGE_MASK;
 	to->tsc_offset          = from->tsc_offset;
@@ -898,6 +901,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	/* Use vmcb01 MMU and format if guest does not use nNPT */
 	if (nested_npt_enabled(svm)) {
 		vmcb02->control.misc_ctl &= ~SVM_MISC_ENABLE_GMET;
+		vmcb02->control.misc_ctl |= (svm->nested.ctl.misc_ctl & SVM_MISC_ENABLE_GMET);
 
 		nested_svm_init_mmu_context(vcpu);
 	}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index fd79874c5f4b..a82471a6d3ea 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5504,6 +5504,9 @@ static __init void svm_set_cpu_caps(void)
 		if (boot_cpu_has(X86_FEATURE_PFTHRESHOLD))
 			kvm_cpu_cap_set(X86_FEATURE_PFTHRESHOLD);
 
+		if (gmet_enabled)
+			kvm_cpu_cap_set(X86_FEATURE_GMET);
+
 		if (vgif)
 			kvm_cpu_cap_set(X86_FEATURE_VGIF);
 
-- 
2.52.0

Re: [PATCH v5 00/28] KVM: combined patchset for MBEC/GMET support

[Paolo Bonzini]

On 4/30/26 17:07, Paolo Bonzini wrote:
> I will once more send you to v3 (https://lore.kernel.org/kvm/20260408154217.458420-1-pbonzini@redhat.com/)
> for the description of the series.
> 
> v4 incorrectly rebased onto 7.1 KVM and broke the case where L1 disables
> NPT.  On top of that I made a few final touches on the patch split, and
> opted to use the XU bit unconditionally in the MMU even if MBEC is disabled.
> This is more consistent with the idea of reducing as much as possible
> the differences between mbec=0 and mbec=1 modes.

I placed this also at branch kvm-mbec of 
https://git.kernel.org/pub/scm/virt/kvm/kvm.git.

Paolo

> Paolo
> 
> v4->v5:
> - patches 8 and 9: swap to clarify use of ACC_USER_MASK to detect read faults
> - patch 11: fix final argument to kvm_translate_gpa (using pte_access instead
>    of walker->pte_access worked more or less accidentally, but it is incorrect
>    because vmx_translate_nested_gpa uses ACC_* constants rather than PT_*)
> - patches 13 and 15: revert to always setting shadow_xu_mask ==
>    VMX_EPT_USER_EXECUTABLE_MASK, even if MBEC is disabled.  The MMU always
>    operates as if MBEC is available, instead of complicating its life (and
>    potentially introducing bugs) by mapping XU onto X; blocking incorrect
>    configuration can be done at higher levels.  Add a comment on the design.
> - patch 24: also block CR4.SMAP
> - patches 26 and 28: fix rebase onto 7.1 KVM (fixes nested NPT disabled)
> 
> v3->v4:
> - patch 15: clear enable_mbec = 0 if enable_ept == 0
> - patches 23-27: adjust for rename of nested_ctl to misc_ctl
> - patch 24: new
> - patch 27: disable svm_get_cpl for SEV-ES/SEV-SNP
> - patch 28: fix commit message reference to __nested_svm_check_controls
> 
> 
> Jon Kohler (5):
>    KVM: TDX/VMX: rework EPT_VIOLATION_EXEC_FOR_RING3_LIN into PROT_MASK
>    KVM: x86/mmu: remove SPTE_PERM_MASK
>    KVM: x86/mmu: free up bit 10 of PTEs in preparation for MBEC
>    KVM: nVMX: advertise MBEC to nested guests
>    KVM: nVMX: allow MBEC with EVMCS
> 
> Paolo Bonzini (23):
>    KVM: x86/mmu: shuffle high bits of SPTEs in preparation for MBEC
>    KVM: x86/mmu: remove SPTE_EPT_*
>    KVM: x86/mmu: merge make_spte_{non,}executable
>    KVM: x86/mmu: rename and clarify BYTE_MASK
>    KVM: x86/mmu: separate more EPT/non-EPT permission_fault()
>    KVM: x86/mmu: introduce ACC_READ_MASK
>    KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa
>    KVM: x86/mmu: pass pte_access for final nGPA->GPA walk
>    KVM: x86: make translate_nested_gpa vendor-specific
>    KVM: x86/mmu: split XS/XU bits for EPT
>    KVM: x86/mmu: move cr4_smep to base role
>    KVM: VMX: enable use of MBEC
>    KVM: nVMX: pass advanced EPT violation vmexit info to guest
>    KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations
>    KVM: x86/mmu: add support for MBEC to EPT page table walks
>    KVM: x86/mmu: propagate access mask from root pages down
>    KVM: x86/mmu: introduce cpu_role bit for availability of PFEC.I/D
>    KVM: SVM: add GMET bit definitions
>    KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu
>    KVM: x86/mmu: add support for GMET to NPT page table walks
>    KVM: SVM: enable GMET and set it in MMU role
>    KVM: SVM: work around errata 1218
>    KVM: nSVM: enable GMET for guests
> 
>   Documentation/virt/kvm/x86/mmu.rst |  10 +-
>   arch/x86/include/asm/cpufeatures.h |   1 +
>   arch/x86/include/asm/kvm-x86-ops.h |   1 +
>   arch/x86/include/asm/kvm_host.h    |  48 +++++---
>   arch/x86/include/asm/svm.h         |   1 +
>   arch/x86/include/asm/vmx.h         |  14 ++-
>   arch/x86/kvm/hyperv.c              |   4 +-
>   arch/x86/kvm/mmu.h                 |  30 +++--
>   arch/x86/kvm/mmu/mmu.c             | 176 ++++++++++++++++++++---------
>   arch/x86/kvm/mmu/mmutrace.h        |  19 ++--
>   arch/x86/kvm/mmu/paging_tmpl.h     |  73 ++++++++----
>   arch/x86/kvm/mmu/spte.c            |  92 +++++++++------
>   arch/x86/kvm/mmu/spte.h            |  70 +++++++-----
>   arch/x86/kvm/mmu/tdp_mmu.c         |   6 +-
>   arch/x86/kvm/svm/nested.c          |  38 ++++++-
>   arch/x86/kvm/svm/svm.c             |  31 +++++
>   arch/x86/kvm/svm/svm.h             |   1 +
>   arch/x86/kvm/vmx/capabilities.h    |  12 +-
>   arch/x86/kvm/vmx/common.h          |  20 ++--
>   arch/x86/kvm/vmx/hyperv_evmcs.h    |   1 +
>   arch/x86/kvm/vmx/main.c            |   9 ++
>   arch/x86/kvm/vmx/nested.c          |  46 +++++++-
>   arch/x86/kvm/vmx/tdx.c             |   2 +-
>   arch/x86/kvm/vmx/vmx.c             |  27 ++++-
>   arch/x86/kvm/vmx/vmx.h             |   1 +
>   arch/x86/kvm/vmx/x86_ops.h         |   1 +
>   arch/x86/kvm/x86.c                 |  18 +--
>   27 files changed, 529 insertions(+), 223 deletions(-)
> 

Re: [PATCH v5 00/28] KVM: combined patchset for MBEC/GMET support

[Sean Christopherson]

On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> On 4/30/26 17:07, Paolo Bonzini wrote:
> > I will once more send you to v3 (https://lore.kernel.org/kvm/20260408154217.458420-1-pbonzini@redhat.com/)
> > for the description of the series.
> > 
> > v4 incorrectly rebased onto 7.1 KVM and broke the case where L1 disables
> > NPT.  On top of that I made a few final touches on the patch split, and
> > opted to use the XU bit unconditionally in the MMU even if MBEC is disabled.
> > This is more consistent with the idea of reducing as much as possible
> > the differences between mbec=0 and mbec=1 modes.
> 
> I placed this also at branch kvm-mbec of
> https://git.kernel.org/pub/scm/virt/kvm/kvm.git.

A decent number of nits, but nothing that truly necessitates a respin or rewriting
of history.  I don't have a strong preference between doing fixups versus cleanups
on top.

Re: [PATCH v5 00/28] KVM: combined patchset for MBEC/GMET support

[Paolo Bonzini]

On Thu, Apr 30, 2026 at 9:17 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Thu, Apr 30, 2026, Paolo Bonzini wrote:
> > On 4/30/26 17:07, Paolo Bonzini wrote:
> > > I will once more send you to v3 (https://lore.kernel.org/kvm/20260408154217.458420-1-pbonzini@redhat.com/)
> > > for the description of the series.
> > >
> > > v4 incorrectly rebased onto 7.1 KVM and broke the case where L1 disables
> > > NPT.  On top of that I made a few final touches on the patch split, and
> > > opted to use the XU bit unconditionally in the MMU even if MBEC is disabled.
> > > This is more consistent with the idea of reducing as much as possible
> > > the differences between mbec=0 and mbec=1 modes.
> >
> > I placed this also at branch kvm-mbec of
> > https://git.kernel.org/pub/scm/virt/kvm/kvm.git.
>
> A decent number of nits, but nothing that truly necessitates a respin or rewriting
> of history.  I don't have a strong preference between doing fixups versus cleanups
> on top.

I'll definitely do fixups.

Paolo

[PATCH v6 00/28] KVM: combined patchset for MBEC/GMET support

[Paolo Bonzini]

This version can also be found in the "queue" branch of kvm.git.
Since it should be final I'm including again for reference the full
description.
    
Both MBEC and GMET allow more granular control over execute permissions,
with different levels of separation between supervisor and user mode.
MBEC provides support for separate supervisor and user-mode bits in the
PTEs; GMET instead lacks supervisor-mode only execution (with NX=0,
"both" is represented by U=0 and user-mode only by U=1).  GMET was
clearly inspired by SMEP though with some differences and annoyances.

The implementation starts from two changes to core MMU code, both
of which help making the actual feature almost trivial to implement:

- first, I'm cleaning up the implementation of nVMX exec-only, by
  properly adding read permissions to the ACC_* constant and to the
  permission bitmask machinery.  Jon also had to add a fourth ACC_*
  bit, but used it only in the special case of nested MBEC; here
  instead ACC_READ_MASK is the normality, which simplifies testing
  a lot and removes gratuitous complexity.

- second, I'm enforcing that KVM runs with MBEC/GMET enabled even in
  non-nested mode, if it wants to provide the feature to nested
  hypervisors.  This makes the creation of SPTEs looks exactly the
  same for L1 and L2 guests, despite only the latter using MBEC/GMET
  fully; the difference lies only in the input access permissions.

This strategy adds a limited amount of complexity to the core is limited,
while providing for an almost entirely seamless support of nested
hypervisors.

Later patches have to use slightly different meanings for ACC_* in Intel
and AMD.  On the Intel side, some work is needed in order to split
shadow_x_mask and ACC_EXEC_MASK in two; now that there is an actual
ACC_READ_MASK to be used for exec-only pages, ACC_USER_MASK is unused
and can be reused as ACC_USER_EXEC_MASK.  However, unlike the older
ACC_USER_MASK hack these differences are backed by concrete concepts
of the page table format, and there is always a 1:1 mapping from ACC_*
bits to PT_*_MASK or shadow_*_mask:

                            Intel                 AMD
     --------------------   -------------------   -------------------
     ACC_READ_MASK          PT_PRESENT_MASK       PT_PRESENT_MASK
     ACC_WRITE_MASK         PT_WRITABLE_MASK      PT_WRITABLE_MASK
     ACC_EXEC_MASK          shadow_xs_mask        shadow_nx_mask
     ACC_USER_MASK          ---                   shadow_user_mask
     ACC_USER_EXEC_MASK     shadow_xu_mask        ---

On Intel, ACC_EXEC_MASK is used for kernel-mode execution and is tied to
shadow_xs_mask (when MBEC is disabled, ACC_USER_EXEC_MASK and the XU bit
are computed but ineffective).  update_permission_bitmask() precomputes
all the necessary conditions.  On the AMD side, the U bit maps to
ACC_USER_MASK but nNPT adjusts the permission bitmask to ignore it for
reads and writes when GMET is active.  Despite the smaller scale of the
changes compared to MBEC, there are some changes to make to use GMET
for L1 guests, because the page tables have to be created with U=0.
This means that the root page has role.access != ACC_ALL and its
permissions have to be propagated down.

Note that with MBEC the user/supervisor distinction depends on the U
bit of the page tables rather than the CPL.  Processors provide this
information to the hypervisor through the "advanced EPT violation
vmexit info" feature, which is a requirement for KVM to use MBEC,
and kvm-intel.ko passes it to the MMU in PFERR_USER_MASK (unlike
kvm-amd.ko which computes it from the CPL).  This needs a small change
to pass the effective XWU permissions of the page tables down to
translate_nested_gpa().

The former "smep_andnot_wp" bit of cpu_role.base, now named "cr4_smep",
is repurposed for nested TDP to indicate that MBEC/GMET is on.  The minor
pessimization for shadow page tables (toggling CR4.SMEP now always forces
building a separate version of the shadow page tables, even though that's
technically unnecessary if CR4.WP=1) is not really worth fretting about;
in practice, guests are not going to flip CR4.SMEP in a way that would
prevent efficient reuse of shadow page tables.

Paolo

v5->v6:
- rename make_spte_executable to change_spte_executable
- rename byte index in update_permission_bitmask to index
- use (u8) casts before "KVM: x86/mmu: introduce ACC_READ_MASK"
- make commit message for "KVM: x86/mmu: split XS/XU bits for EPT" more accurate
- add XU to shadow_acc_track_mask already in "KVM: x86/mmu: split XS/XU bits for EPT"
- fix compilation error
- use alternative code for __vmx_handle_ept_violation suggested by Sean


Jon Kohler (5):
  KVM: TDX/VMX: rework EPT_VIOLATION_EXEC_FOR_RING3_LIN into PROT_MASK
  KVM: x86/mmu: remove SPTE_PERM_MASK
  KVM: x86/mmu: free up bit 10 of PTEs in preparation for MBEC
  KVM: nVMX: advertise MBEC to nested guests
  KVM: nVMX: allow MBEC with EVMCS

Paolo Bonzini (23):
  KVM: x86/mmu: shuffle high bits of SPTEs in preparation for MBEC
  KVM: x86/mmu: remove SPTE_EPT_*
  KVM: x86/mmu: merge make_spte_{non,}executable
  KVM: x86/mmu: rename and clarify BYTE_MASK
  KVM: x86/mmu: separate more EPT/non-EPT permission_fault()
  KVM: x86/mmu: introduce ACC_READ_MASK
  KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa
  KVM: x86/mmu: pass pte_access for final nGPA->GPA walk
  KVM: x86: make translate_nested_gpa vendor-specific
  KVM: x86/mmu: split XS/XU bits for EPT
  KVM: x86/mmu: move cr4_smep to base role
  KVM: VMX: enable use of MBEC
  KVM: nVMX: pass advanced EPT violation vmexit info to guest
  KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations
  KVM: x86/mmu: add support for MBEC to EPT page table walks
  KVM: x86/mmu: propagate access mask from root pages down
  KVM: x86/mmu: introduce cpu_role bit for availability of PFEC.I/D
  KVM: SVM: add GMET bit definitions
  KVM: x86/mmu: hard code more bits in kvm_init_shadow_npt_mmu
  KVM: x86/mmu: add support for GMET to NPT page table walks
  KVM: SVM: enable GMET and set it in MMU role
  KVM: SVM: work around errata 1218
  KVM: nSVM: enable GMET for guests

 Documentation/virt/kvm/x86/mmu.rst |  10 +-
 arch/x86/include/asm/cpufeatures.h |   1 +
 arch/x86/include/asm/kvm-x86-ops.h |   1 +
 arch/x86/include/asm/kvm_host.h    |  48 +++++---
 arch/x86/include/asm/svm.h         |   1 +
 arch/x86/include/asm/vmx.h         |  14 ++-
 arch/x86/kvm/hyperv.c              |   4 +-
 arch/x86/kvm/mmu.h                 |  30 +++--
 arch/x86/kvm/mmu/mmu.c             | 182 ++++++++++++++++++++---------
 arch/x86/kvm/mmu/mmutrace.h        |  19 +--
 arch/x86/kvm/mmu/paging_tmpl.h     |  73 ++++++++----
 arch/x86/kvm/mmu/spte.c            |  92 +++++++++------
 arch/x86/kvm/mmu/spte.h            |  70 ++++++-----
 arch/x86/kvm/mmu/tdp_mmu.c         |   6 +-
 arch/x86/kvm/svm/nested.c          |  38 +++++-
 arch/x86/kvm/svm/svm.c             |  31 +++++
 arch/x86/kvm/svm/svm.h             |   1 +
 arch/x86/kvm/vmx/capabilities.h    |  12 +-
 arch/x86/kvm/vmx/common.h          |  26 +++--
 arch/x86/kvm/vmx/hyperv_evmcs.h    |   1 +
 arch/x86/kvm/vmx/main.c            |   9 ++
 arch/x86/kvm/vmx/nested.c          |  46 +++++++-
 arch/x86/kvm/vmx/tdx.c             |   2 +-
 arch/x86/kvm/vmx/vmx.c             |  27 ++++-
 arch/x86/kvm/vmx/vmx.h             |   1 +
 arch/x86/kvm/vmx/x86_ops.h         |   1 +
 arch/x86/kvm/x86.c                 |  18 +--
 27 files changed, 536 insertions(+), 228 deletions(-)

-- 
2.54.0

[PATCH 12/28] KVM: x86: make translate_nested_gpa vendor-specific

[Paolo Bonzini]

EPT and NPT have different rules for passing PFERR_USER_MASK to the
nested page table walk.  In particular, for final addresses EPT
uses the U bit of the guest (nGVA->nGPA) walk.

While at it, remove PFERR_USER_MASK from the VMX version of the
function, since it is actually ignored by the tables that
update_permission_bitmask() generates for EPT.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  4 ++++
 arch/x86/kvm/hyperv.c           |  3 ++-
 arch/x86/kvm/mmu.h              |  9 +++------
 arch/x86/kvm/svm/nested.c       | 15 +++++++++++++++
 arch/x86/kvm/vmx/nested.c       | 12 ++++++++++++
 arch/x86/kvm/x86.c              | 16 ----------------
 6 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8f2a1b915df9..62dc782b2dd3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2010,6 +2010,10 @@ struct kvm_x86_nested_ops {
 			 struct kvm_nested_state *kvm_state);
 	bool (*get_nested_state_pages)(struct kvm_vcpu *vcpu);
 	int (*write_log_dirty)(struct kvm_vcpu *vcpu, gpa_t l2_gpa);
+	gpa_t (*translate_nested_gpa)(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access);
 
 	int (*enable_evmcs)(struct kvm_vcpu *vcpu,
 			    uint16_t *vmcs_version);
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 53688f7b76eb..f35fae3a7b3d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2041,7 +2041,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 	 * read with kvm_read_guest().
 	 */
 	if (!hc->fast && is_guest_mode(vcpu)) {
-		hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa,
+		hc->ingpa = kvm_x86_ops.nested_ops->translate_nested_gpa(
+					vcpu, hc->ingpa,
 					PFERR_GUEST_FINAL_MASK, NULL, 0);
 		if (unlikely(hc->ingpa == INVALID_GPA))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 635c2e5d8513..63be5c5efed9 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -294,10 +294,6 @@ static inline void kvm_update_page_stats(struct kvm *kvm, int level, int count)
 	atomic64_add(count, &kvm->stat.pages[level - 1]);
 }
 
-gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception,
-			   u64 pte_access);
-
 static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 				      struct kvm_mmu *mmu,
 				      gpa_t gpa, u64 access,
@@ -306,8 +302,9 @@ static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 {
 	if (mmu != &vcpu->arch.nested_mmu)
 		return gpa;
-	return translate_nested_gpa(vcpu, gpa, access, exception,
-				    pte_access);
+	return kvm_x86_ops.nested_ops->translate_nested_gpa(vcpu, gpa, access,
+							    exception,
+							    pte_access);
 }
 
 static inline bool kvm_has_mirrored_tdp(const struct kvm *kvm)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 961804df5f45..df232153eb24 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -2071,8 +2071,23 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static gpa_t svm_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access)
+{
+	struct kvm_mmu *mmu = vcpu->arch.mmu;
+
+	BUG_ON(!mmu_is_nested(vcpu));
+
+	/* NPT walks are always user-walks */
+	access |= PFERR_USER_MASK;
+	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
+}
+
 struct kvm_x86_nested_ops svm_nested_ops = {
 	.leave_nested = svm_leave_nested,
+	.translate_nested_gpa = svm_translate_nested_gpa,
 	.is_exception_vmexit = nested_svm_is_exception_vmexit,
 	.check_events = svm_check_nested_events,
 	.triple_fault = nested_svm_triple_fault,
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3fe88f29be7a..cd1924c6e075 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7438,8 +7438,20 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
 	return 0;
 }
 
+static gpa_t vmx_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access)
+{
+	struct kvm_mmu *mmu = vcpu->arch.mmu;
+
+	BUG_ON(!mmu_is_nested(vcpu));
+	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
+}
+
 struct kvm_x86_nested_ops vmx_nested_ops = {
 	.leave_nested = vmx_leave_nested,
+	.translate_nested_gpa = vmx_translate_nested_gpa,
 	.is_exception_vmexit = nested_vmx_is_exception_vmexit,
 	.check_events = vmx_check_nested_events,
 	.has_events = vmx_has_nested_events,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 67979b7de5d6..7c6942afae81 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7848,22 +7848,6 @@ void kvm_get_segment(struct kvm_vcpu *vcpu,
 	kvm_x86_call(get_segment)(vcpu, var, seg);
 }
 
-gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception,
-			   u64 pte_access)
-{
-	struct kvm_mmu *mmu = vcpu->arch.mmu;
-	gpa_t t_gpa;
-
-	BUG_ON(!mmu_is_nested(vcpu));
-
-	/* NPT walks are always user-walks */
-	access |= PFERR_USER_MASK;
-	t_gpa  = mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
-
-	return t_gpa;
-}
-
 gpa_t kvm_mmu_gva_to_gpa_read(struct kvm_vcpu *vcpu, gva_t gva,
 			      struct x86_exception *exception)
 {
-- 
2.54.0

[PATCH v4 00/28] KVM: combined patchset for MBEC/GMET support

[Paolo Bonzini]

I will send you to v3 (https://lore.kernel.org/kvm/20260408154217.458420-1-pbonzini@redhat.com/)
for the description of the series, and leave a short list of changes:

- patch 15: clear enable_mbec = 0 if enable_ept == 0
- patches 23-27: adjust for rename of nested_ctl to misc_ctl
- patch 24: new
- patch 27: disable svm_get_cpl for SEV-ES/SEV-SNP
- patch 28: fix commit message reference to __nested_svm_check_controls 

(patch 24 is the only major bugfix).

Thanks,

Paolo

Jon Kohler (5):
  KVM: TDX/VMX: rework EPT_VIOLATION_EXEC_FOR_RING3_LIN into PROT_MASK
  KVM: x86/mmu: remove SPTE_PERM_MASK
  KVM: x86/mmu: free up bit 10 of PTEs in preparation for MBEC
  KVM: nVMX: advertise MBEC to nested guests
  KVM: nVMX: allow MBEC with EVMCS

Paolo Bonzini (23):
  KVM: x86/mmu: shuffle high bits of SPTEs in preparation for MBEC
  KVM: x86/mmu: remove SPTE_EPT_*
  KVM: x86/mmu: merge make_spte_{non,}executable
  KVM: x86/mmu: rename and clarify BYTE_MASK
  KVM: x86/mmu: introduce ACC_READ_MASK
  KVM: x86/mmu: separate more EPT/non-EPT permission_fault()
  KVM: x86/mmu: pass PFERR_GUEST_PAGE/FINAL_MASK to kvm_translate_gpa
  KVM: x86/mmu: pass pte_access for final nGPA->GPA walk
  KVM: x86: make translate_nested_gpa vendor-specific
  KVM: x86/mmu: split XS/XU bits for EPT
  KVM: x86/mmu: move cr4_smep to base role
  KVM: VMX: enable use of MBEC
  KVM: nVMX: pass advanced EPT violation vmexit info to guest
  KVM: nVMX: pass PFERR_USER_MASK to MMU on EPT violations
  KVM: x86/mmu: add support for MBEC to EPT page table walks
  KVM: x86/mmu: propagate access mask from root pages down
  KVM: x86/mmu: introduce cpu_role bit for availability of PFEC.I/D
  KVM: SVM: add GMET bit definitions
  KVM: x86/mmu: set CR0.WP=1 for shadow NPT MMU
  KVM: x86/mmu: add support for GMET to NPT page table walks
  KVM: SVM: enable GMET and set it in MMU role
  KVM: SVM: work around errata 1218
  KVM: nSVM: enable GMET for guests

 Documentation/virt/kvm/x86/mmu.rst |  10 +-
 arch/x86/include/asm/cpufeatures.h |   1 +
 arch/x86/include/asm/kvm-x86-ops.h |   1 +
 arch/x86/include/asm/kvm_host.h    |  48 ++++++---
 arch/x86/include/asm/svm.h         |   1 +
 arch/x86/include/asm/vmx.h         |  14 ++-
 arch/x86/kvm/hyperv.c              |   4 +-
 arch/x86/kvm/mmu.h                 |  30 ++++--
 arch/x86/kvm/mmu/mmu.c             | 168 ++++++++++++++++++++---------
 arch/x86/kvm/mmu/mmutrace.h        |  19 ++--
 arch/x86/kvm/mmu/paging_tmpl.h     |  73 ++++++++-----
 arch/x86/kvm/mmu/spte.c            |  74 +++++++------
 arch/x86/kvm/mmu/spte.h            |  70 ++++++------
 arch/x86/kvm/mmu/tdp_mmu.c         |   6 +-
 arch/x86/kvm/svm/nested.c          |  37 ++++++-
 arch/x86/kvm/svm/svm.c             |  31 ++++++
 arch/x86/kvm/svm/svm.h             |   1 +
 arch/x86/kvm/vmx/capabilities.h    |  12 ++-
 arch/x86/kvm/vmx/common.h          |  20 ++--
 arch/x86/kvm/vmx/hyperv_evmcs.h    |   1 +
 arch/x86/kvm/vmx/main.c            |   9 ++
 arch/x86/kvm/vmx/nested.c          |  46 +++++++-
 arch/x86/kvm/vmx/tdx.c             |   2 +-
 arch/x86/kvm/vmx/vmx.c             |  27 ++++-
 arch/x86/kvm/vmx/vmx.h             |   1 +
 arch/x86/kvm/vmx/x86_ops.h         |   1 +
 arch/x86/kvm/x86.c                 |  18 +---
 27 files changed, 505 insertions(+), 220 deletions(-)

-- 
2.52.0

[PATCH 12/28] KVM: x86: make translate_nested_gpa vendor-specific

[Paolo Bonzini]

EPT and NPT have different rules for passing PFERR_USER_MASK to the
nested page table walk.  In particular, for final addresses EPT
uses the U bit of the guest (nGVA->nGPA) walk.

While at it, remove PFERR_USER_MASK from the VMX version of the
function, since it is actually ignored by the tables that
update_permission_bitmask() generates for EPT.

Tested-by: David Riley <d.riley@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  4 ++++
 arch/x86/kvm/hyperv.c           |  3 ++-
 arch/x86/kvm/mmu.h              |  9 +++------
 arch/x86/kvm/svm/nested.c       | 15 +++++++++++++++
 arch/x86/kvm/vmx/nested.c       | 12 ++++++++++++
 arch/x86/kvm/x86.c              | 16 ----------------
 6 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8f2a1b915df9..62dc782b2dd3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2010,6 +2010,10 @@ struct kvm_x86_nested_ops {
 			 struct kvm_nested_state *kvm_state);
 	bool (*get_nested_state_pages)(struct kvm_vcpu *vcpu);
 	int (*write_log_dirty)(struct kvm_vcpu *vcpu, gpa_t l2_gpa);
+	gpa_t (*translate_nested_gpa)(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access);
 
 	int (*enable_evmcs)(struct kvm_vcpu *vcpu,
 			    uint16_t *vmcs_version);
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 53688f7b76eb..f35fae3a7b3d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2041,7 +2041,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 	 * read with kvm_read_guest().
 	 */
 	if (!hc->fast && is_guest_mode(vcpu)) {
-		hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa,
+		hc->ingpa = kvm_x86_ops.nested_ops->translate_nested_gpa(
+					vcpu, hc->ingpa,
 					PFERR_GUEST_FINAL_MASK, NULL, 0);
 		if (unlikely(hc->ingpa == INVALID_GPA))
 			return HV_STATUS_INVALID_HYPERCALL_INPUT;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 635c2e5d8513..63be5c5efed9 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -294,10 +294,6 @@ static inline void kvm_update_page_stats(struct kvm *kvm, int level, int count)
 	atomic64_add(count, &kvm->stat.pages[level - 1]);
 }
 
-gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception,
-			   u64 pte_access);
-
 static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 				      struct kvm_mmu *mmu,
 				      gpa_t gpa, u64 access,
@@ -306,8 +302,9 @@ static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 {
 	if (mmu != &vcpu->arch.nested_mmu)
 		return gpa;
-	return translate_nested_gpa(vcpu, gpa, access, exception,
-				    pte_access);
+	return kvm_x86_ops.nested_ops->translate_nested_gpa(vcpu, gpa, access,
+							    exception,
+							    pte_access);
 }
 
 static inline bool kvm_has_mirrored_tdp(const struct kvm *kvm)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 961804df5f45..df232153eb24 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -2071,8 +2071,23 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static gpa_t svm_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access)
+{
+	struct kvm_mmu *mmu = vcpu->arch.mmu;
+
+	BUG_ON(!mmu_is_nested(vcpu));
+
+	/* NPT walks are always user-walks */
+	access |= PFERR_USER_MASK;
+	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
+}
+
 struct kvm_x86_nested_ops svm_nested_ops = {
 	.leave_nested = svm_leave_nested,
+	.translate_nested_gpa = svm_translate_nested_gpa,
 	.is_exception_vmexit = nested_svm_is_exception_vmexit,
 	.check_events = svm_check_nested_events,
 	.triple_fault = nested_svm_triple_fault,
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3fe88f29be7a..cd1924c6e075 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7438,8 +7438,20 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
 	return 0;
 }
 
+static gpa_t vmx_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa,
+				      u64 access,
+				      struct x86_exception *exception,
+				      u64 pte_access)
+{
+	struct kvm_mmu *mmu = vcpu->arch.mmu;
+
+	BUG_ON(!mmu_is_nested(vcpu));
+	return mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
+}
+
 struct kvm_x86_nested_ops vmx_nested_ops = {
 	.leave_nested = vmx_leave_nested,
+	.translate_nested_gpa = vmx_translate_nested_gpa,
 	.is_exception_vmexit = nested_vmx_is_exception_vmexit,
 	.check_events = vmx_check_nested_events,
 	.has_events = vmx_has_nested_events,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 67979b7de5d6..7c6942afae81 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7848,22 +7848,6 @@ void kvm_get_segment(struct kvm_vcpu *vcpu,
 	kvm_x86_call(get_segment)(vcpu, var, seg);
 }
 
-gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
-			   struct x86_exception *exception,
-			   u64 pte_access)
-{
-	struct kvm_mmu *mmu = vcpu->arch.mmu;
-	gpa_t t_gpa;
-
-	BUG_ON(!mmu_is_nested(vcpu));
-
-	/* NPT walks are always user-walks */
-	access |= PFERR_USER_MASK;
-	t_gpa  = mmu->gva_to_gpa(vcpu, mmu, gpa, access, exception);
-
-	return t_gpa;
-}
-
 gpa_t kvm_mmu_gva_to_gpa_read(struct kvm_vcpu *vcpu, gva_t gva,
 			      struct x86_exception *exception)
 {
-- 
2.52.0